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Answer 185329 by jim_thompson5910(28595) on 2010-01-02 17:01:57 (Show Source):
You can put this solution on YOUR website! Start with the first equation.
 Multiply both sides by the LCD  to clear any fractions.
 Distribute and multiply.
----------------------------------------------------------------------------
 Move onto the second equation.
 Multiply both sides by the LCD  to clear any fractions.
 Distribute and multiply.
----------------------------------------------------------------------------
So we now have the system of equations
and it turns out that the solution to that system above is the same solution to the original system of equations.
Start with the given system of equations:
 Multiply the both sides of the first equation by 4.
 Distribute and multiply.
 Multiply the both sides of the second equation by 5.
 Distribute and multiply.
So we have the new system of equations:
Now add the equations together. You can do this by simply adding the two left sides and the two right sides separately like this:
 Group like terms.
 Combine like terms.
 Simplify.
 Divide both sides by  to isolate  .
 Reduce.
------------------------------------------------------------------
 Now go back to the first equation.
 Plug in  .
 Multiply.
 Subtract  from both sides.
 Combine like terms on the right side.
 Divide both sides by  to isolate  .
 Reduce.
So the solutions are  and  .
Which form the ordered pair ) .
This means that the system is consistent and independent.
Notice when we graph the equations, we see that they intersect at ) . So this visually verifies our answer.
 Graph of  (red) and  (green)
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Graphs/253101: -5x+6=x+12 Help? 1 solutions
Answer 185325 by jim_thompson5910(28595) on 2010-01-02 16:31:39 (Show Source):
You can put this solution on YOUR website!
 Start with the given equation.
 Subtract  from both sides.
 Subtract  from both sides.
 Combine like terms on the left side.
 Combine like terms on the right side.
 Divide both sides by  to isolate  .
 Reduce.
----------------------------------------------------------------------
Answer:
So the solution is
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Quadratic_Equations/253100: The square of a negative integer minus itself is 110. Find the integer. 1 solutions
Answer 185324 by jim_thompson5910(28595) on 2010-01-02 16:31:00 (Show Source):
You can put this solution on YOUR website!Since "The square of a negative integer minus itself is 110", this means that
 Start with the given equation.
 Subtract 110 from both sides.
Notice that the quadratic  is in the form of  where  ,  , and
Let's use the quadratic formula to solve for "x":
 Start with the quadratic formula
 Plug in  ,  , and
 Negate  to get  .
 Square  to get  .
 Multiply  to get
 Rewrite  as
 Add  to  to get
 Multiply  and  to get  .
 Take the square root of  to get  .
 or  Break up the expression.
 or  Combine like terms.
 or  Simplify.
So the possible solutions are  or
But since we're told that the integer is negative, this means that the only solution is
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Complex_Numbers/253081: How do you simplify: (x+3)/(6) divided by 1+(x/3)
*note* / = fractions 1 solutions
Answer 185285 by jim_thompson5910(28595) on 2010-01-02 14:35:41 (Show Source):
You can put this solution on YOUR website! Start with the given expression.
 Multiply EVERY term by the inner LCD 6 to clear out the inner fractions.
 Simplify
 Factor the denominator.
 Rearrange the terms.
 Cancel out the common terms.
 Simplify.
So  simplifies to
In other words,
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Numbers_Word_Problems/252970: What is he product of positive integers a and b such that a is greater than b and 1/a+1/b=1/ab=1? 1 solutions
Answer 185178 by jim_thompson5910(28595) on 2010-01-01 22:06:11 (Show Source):
You can put this solution on YOUR website!Well if 'a' and 'b' are both integers, then ab ('a' times 'b') is also an integer because the product of two integers is always an integer. Because  , this means that  if we multiply both sides by ab. Since 1 is the only factor of 1, this tells us that 1=1*1 and that a=1 and b=1.
So if 'a' and 'b' are both positive integers and  , then  ,  , and
So either there's a typo somewhere or you copied the problem incorrectly. Please double check the problem.
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Proofs/251007: There is only one premise, and the conclusion has different letters
Here it is:
A -> B
We have to show (A & C) -> B 1 solutions
Answer 185034 by jim_thompson5910(28595) on 2010-01-01 13:14:01 (Show Source):
You can put this solution on YOUR website!If we use the addition property, we go from A -> B to (A -> B) V ~C (the "V" stands for 'or' and "~" stands for 'not')
Rearrange the terms to get ~C V (A -> B) and then use material implication to get C -> (A -> B). From here, use exportation to get (C & A) -> B and then use commutation to get (A & C) -> B. This derivation is pretty straightforward, but the only trick here is the addition of ~C.
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Miscellaneous_Word_Problems/252853: you throw a basketball up in the air. the basketball's height in feet, is given by the function h=-16t^2+30t+4, where t is the time in seconds after the ball leaves your hand.find the greatest height the ball reaches. 1 solutions
Answer 184954 by jim_thompson5910(28595) on 2009-12-31 16:23:26 (Show Source):
You can put this solution on YOUR website!The max height is at the vertex.
In order to find the vertex, we first need to find the t-coordinate of the vertex.
To find the t-coordinate of the vertex, use this formula:  .
 Start with the given formula.
From  , we can see that  ,  , and  .
 Plug in  and  .
 Multiply 2 and  to get  .
 Reduce.
So the t-coordinate of the vertex is  .
Now that we know the t-coordinate of the vertex, we can use it to find the h-coordinate of the vertex.
 Start with the given equation.
 Plug in  .
 Square  to get  .
 Multiply  and  to get  .
 Multiply  and  to get  .
 Combine like terms.
So the h-coordinate of the vertex is  .
So the vertex is ) .
This means that the max height is  which is  feet.
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Linear-equations/252733: find the slope of the line that passes through the given points.
Ok are book a little messed up. we are learning about SLopes in Algebra andGeometry
A(5,8) B(7,11)
E(-1,-2), F(-6,-4)
if you could please help me. I need a lot of help. 1 solutions
Answer 184795 by jim_thompson5910(28595) on 2009-12-30 17:34:59 (Show Source):
You can put this solution on YOUR website!Let's find the slope of the line through the points A(5,8) and B(7,11)
Note: ) is the first point ) . So this means that  and  .
Also, ) is the second point ) . So this means that  and  .
 Start with the slope formula.
 Plug in  ,  ,  , and
 Subtract  from  to get
 Subtract  from  to get
So the slope of the line that goes through the points ) and ) is
======================================================================
Now let's find the slope of the line through the points E(-1,-2) and F(-6,-4)
Note: ) is the first point ) . So this means that  and  .
Also, ) is the second point ) . So this means that  and  .
 Start with the slope formula.
 Plug in  ,  ,  , and
 Subtract  from  to get
 Subtract  from  to get
 Reduce
So the slope of the line that goes through the points ) and ) is
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Linear-equations/252731: ok well we are doing this in geometry but its a review from algebra
P(2,5); 4x-y=8
We have to write and equation of the line that passes through the point p and is perpendicular to the line with the given equation
p(1,4); y=2x+4
P(5,3); y=5x+2
If you could please help because i am not following very well in my class 1 solutions
Answer 184794 by jim_thompson5910(28595) on 2009-12-30 17:32:47 (Show Source):
You can put this solution on YOUR website!# 1
 Start with the given equation.
 Subtract  from both sides.
 Rearrange the terms.
 Divide both sides by  to isolate y.
 Break up the fraction.
 Reduce.
We can see that the equation  has a slope  and a y-intercept  .
Now to find the slope of the perpendicular line, simply flip the slope  to get  . Now change the sign to get  . So the perpendicular slope is  .
Now let's use the point slope formula to find the equation of the perpendicular line by plugging in the slope  and the coordinates of the given point ) .
 Start with the point slope formula
 Plug in  ,  , and
 Distribute
 Multiply
 Add 5 to both sides.
 Combine like terms. note: If you need help with fractions, check out this solver.
So the equation of the line perpendicular to  that goes through the point ) is  .
Here's a graph to visually verify our answer:
Graph of the original equation  (red) and the perpendicular line  (green) through the point ) .
==================================================================
# 2
We can see that the equation  has a slope  and a y-intercept  .
Now to find the slope of the perpendicular line, simply flip the slope  to get  . Now change the sign to get  . So the perpendicular slope is  .
Now let's use the point slope formula to find the equation of the perpendicular line by plugging in the slope  and the coordinates of the given point ) .
 Start with the point slope formula
 Plug in  ,  , and
 Distribute
 Multiply
 Add 4 to both sides.
 Combine like terms. note: If you need help with fractions, check out this solver.
So the equation of the line perpendicular to  that goes through the point ) is  .
Here's a graph to visually verify our answer:
Graph of the original equation  (red) and the perpendicular line  (green) through the point ) .
==================================================================
# 3
We can see that the equation  has a slope  and a y-intercept  .
Now to find the slope of the perpendicular line, simply flip the slope  to get  . Now change the sign to get  . So the perpendicular slope is  .
Now let's use the point slope formula to find the equation of the perpendicular line by plugging in the slope  and the coordinates of the given point ) .
 Start with the point slope formula
 Plug in  ,  , and
 Distribute
 Multiply
 Add 3 to both sides.
 Combine like terms.
So the equation of the line perpendicular to  that goes through the point ) is  .
Here's a graph to visually verify our answer:
Graph of the original equation  (red) and the perpendicular line  (green) through the point ) .
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Matrices-and-determiminant/252724: how do i use cramer's rule for three equations on this problem
5x-6y=7+7z
6x-4y+10z=-34
2x+4y=29+3z 1 solutions
Answer 184789 by jim_thompson5910(28595) on 2009-12-30 16:39:56 (Show Source):
You can put this solution on YOUR website!The first goal is to get all of the variable terms to the left side for each equation.
 Start with the first equation.
 Subtract 7z from both sides.
---------------------
 Move onto the third equation.
 Subtract 3z from both sides.
-----------------------
So we now have the system
Now let's use Cramer's Rule to solve this system
| Solved by pluggable solver: Using Cramer's Rule to Solve Systems with 3 variables |

First let . This is the matrix formed by the coefficients of the given system of equations.
Take note that the right hand values of the system are , , and and they are highlighted here:

These values are important as they will be used to replace the columns of the matrix A.
Now let's calculate the the determinant of the matrix A to get . To save space, I'm not showing the calculations for the determinant. However, if you need help with calculating the determinant of the matrix A, check out this solver.
Notation note: denotes the determinant of the matrix A.
---------------------------------------------------------
Now replace the first column of A (that corresponds to the variable 'x') with the values that form the right hand side of the system of equations. We will denote this new matrix (since we're replacing the 'x' column so to speak).

Now compute the determinant of to get . Again, as a space saver, I didn't include the calculations of the determinant. Check out this solver to see how to find this determinant.
To find the first solution, simply divide the determinant of by the determinant of to get: 
So the first solution is 
---------------------------------------------------------
We'll follow the same basic idea to find the other two solutions. Let's reset by letting again (this is the coefficient matrix).
Now replace the second column of A (that corresponds to the variable 'y') with the values that form the right hand side of the system of equations. We will denote this new matrix (since we're replacing the 'y' column in a way).

Now compute the determinant of to get .
To find the second solution, divide the determinant of by the determinant of to get: 
So the second solution is 
---------------------------------------------------------
Let's reset again by letting which is the coefficient matrix.
Replace the third column of A (that corresponds to the variable 'z') with the values that form the right hand side of the system of equations. We will denote this new matrix

Now compute the determinant of to get .
To find the third solution, divide the determinant of by the determinant of to get: 
So the third solution is 
====================================================================================
Final Answer:
So the three solutions are , , and giving the ordered triple (2, 4, -3)
Note: there is a lot of work that is hidden in finding the determinants. Take a look at this 3x3 Determinant Solver to see how to get each determinant.
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If you need more help or practice with Cramer's Rule, check out this solver.
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Linear-equations/252646: 11+6x=2x-13 1 solutions
Answer 184677 by jim_thompson5910(28595) on 2009-12-29 22:45:24 (Show Source):
You can put this solution on YOUR website!
 Start with the given equation.
 Subtract  from both sides.
 Subtract  from both sides.
 Combine like terms on the left side.
 Combine like terms on the right side.
 Divide both sides by  to isolate  .
 Reduce.
----------------------------------------------------------------------
Answer:
So the solution is
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Square-cubic-other-roots/252641: Sarah needs to make a cake and some cookies. The cake requires 3/8 cup of sugar and the cookies require 3/5 cup of sugar. Sarah has 15/16 cups of sugar. Does she have enough sugar, or how much more does she need? 1 solutions
Answer 184673 by jim_thompson5910(28595) on 2009-12-29 21:55:35 (Show Source):
You can put this solution on YOUR website!Simply add the two fractions  and  to get:
So she'll need  cups of sugar. Now the question is: which fraction is larger,  or  ?
To answer this question, first assume that they are equal:
 Cross multiply
 Multiply
 Now change the equal sign '=' to a less than sign '<' (since 600 is less than 624).
Because the left side is less than the right, this means that the left side of  is smaller than the right. So change the '=' to a '<' to get
Since  is smaller than  , this means that she has less sugar than what she needs. So she does NOT have enough sugar.
--------------------------------------------------------------------
How much does she need then? Well let's figure that out.
To find that out, just subtract the amount she has (  ) from the amount she needs (  ) to get:
So she needs  of a cup of sugar.
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Equations/252640: slope 9 and y intercept (0,8)
y= 1 solutions
Answer 184672 by jim_thompson5910(28595) on 2009-12-29 21:43:16 (Show Source):
You can put this solution on YOUR website!
If you want to find the equation of line with a given a slope of  which goes through the point (  ,  ), you can simply use the point-slope formula to find the equation:
---Point-Slope Formula---
 where  is the slope, and ) is the given point
So lets use the Point-Slope Formula to find the equation of the line
 Plug in  ,  , and  (these values are given)
 Distribute
 Multiply  and  to get
 Add 8 to both sides to isolate y
 Combine like terms  and  to get
------------------------------------------------------------------------------------------------------------
Answer:
So the equation of the line with a slope of  which goes through the point (  ,  ) is:
 which is now in  form where the slope is  and the y-intercept is
Notice if we graph the equation  and plot the point (  ,  ), we get (note: if you need help with graphing, check out this solver)
Graph of through the point ( , )
and we can see that the point lies on the line. Since we know the equation has a slope of and goes through the point ( , ), this verifies our answer.
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Equations/252629: 1. The sides of the quadrilateral are consecutive numbers. If the perimeter is 162, how long is each side? 1 solutions
Answer 184650 by jim_thompson5910(28595) on 2009-12-29 20:29:24 (Show Source):
You can put this solution on YOUR website!Let x = length of first side.
Since "The sides of the quadrilateral are consecutive numbers", this means that the side lengths are: x, x+1, x+2, and x+3. Also, because the perimeter is 162, we know that  (just add up the four sides and set the sum equal to 162).
 Start with the given equation.
 Combine like terms on the left side.
 Subtract  from both sides.
 Combine like terms on the right side.
 Divide both sides by  to isolate  .
 Reduce.
----------------------------------------------------------------------
Answer:
So the solution is  giving the four sides to be:
x = 39
x+1 = 40
x+2 = 41
x+3 = 42
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Equations/252631: the hypotenuse of a right triangle is 20 inches. one of the legs has a meadure of 16 inches. what is the measure of the other leg?
the answer i got was not an option 1 solutions
Answer 184648 by jim_thompson5910(28595) on 2009-12-29 20:26:55 (Show Source):
You can put this solution on YOUR website!
We basically have this triangle set up:
To find the unknown length, we need to use the Pythagorean Theorem.
Remember, the Pythagorean Theorem is  where "a" and "b" are the legs of a triangle and "c" is the hypotenuse.
Since the legs are  and  this means that  and
Also, since the hypotenuse is  , this means that  .
 Start with the Pythagorean theorem.
 Plug in  ,  ,
 Square  to get  .
 Square  to get  .
 Subtract  from both sides.
 Combine like terms.
 Take the square root of both sides. Note: only the positive square root is considered (since a negative length doesn't make sense).
 Simplify the square root.
================================================================
Answer:
So the solution is  which means that the measure of the remaining leg is 12 inches.
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Linear-equations/252628: Find an equation of the line passing through the point (5,4) and parallel to the line whose equation
is 2x + y = 3. 1 solutions
Answer 184647 by jim_thompson5910(28595) on 2009-12-29 20:09:47 (Show Source):
You can put this solution on YOUR website!
 Start with the given equation.
 Subtract  from both sides.
 Rearrange the terms.
We can see that the equation  has a slope  and a y-intercept  .
Since parallel lines have equal slopes, this means that we know that the slope of the unknown parallel line is  .
Now let's use the point slope formula to find the equation of the parallel line by plugging in the slope  and the coordinates of the given point ) .
 Start with the point slope formula
 Plug in  ,  , and
 Distribute
 Multiply
 Add 4 to both sides.
 Combine like terms.
So the equation of the line parallel to  that goes through the point ) is  .
Here's a graph to visually verify our answer:
Graph of the original equation  (red) and the parallel line  (green) through the point ) .
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Probability-and-statistics/252627: Can I please get some assistance with the formula for e.
2. U.S. Population by Region. The U.S. population by region (in millions) for selected years is given in the table. Find the probability that a U.S. resident selected at random satisfies the following:
e.) What are the odds that a randomly selected U.S. resident in 2000 was not from the South?
REGION 1995 1997 2000
Northwest 51.4 51.6 53.6
Midwest 61.8 62.5 64.4
South 91.8 94.2 100.2
West 57.7 59.4 63.2
TOTAL 262.7 267.7 281.4
Answer: 302 to 167
1 solutions
Answer 184646 by jim_thompson5910(28595) on 2009-12-29 20:06:39 (Show Source):
You can put this solution on YOUR website!Note: Because we're only concerned with the year 2000, we'll only draw values from the last column.
To find the probability that you select a resident at random that is NOT in the south, simply note that probability that you select an individual that does live in the south is...
P(Resident from the South) = Number of Residents Who Live in the South/Total US Residents = 100.2/281.4 = 0.35608
So the probability of choosing someone from the south is about 0.35608 (about a 35.6% chance).
Since we want everything but residents from the South, just subtract this probability from 1 (ie 100%) to get:
1-0.35608 = 0.64392
So the probability of selecting a resident that is NOT from the South in the year 2000 is 0.64392 (which is about a 64.4% chance)
Another way to do this is to add up all of the data values in the 2000 column that are NOT the south and divide them by the total 281.4
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absolute-value/252622: Solve the inequality and graph the solution set:
|3k + 8| > -9
1 solutions
Answer 184642 by jim_thompson5910(28595) on 2009-12-29 19:15:10 (Show Source):
You can put this solution on YOUR website!Because the absolute value of any number is ALWAYS positive, this means that  for any value of 'k'. So  is ALWAYS true for any value of 'k'. So there are an infinite number of solutions. To graph the solution set, just shade the entire number line.
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absolute-value/252621: Find the absolute value:
|3x+4|+11 = 4
1 solutions
Answer 184640 by jim_thompson5910(28595) on 2009-12-29 19:12:49 (Show Source):
You can put this solution on YOUR website!
 Start with the given equation
 Subtract 11 from both sides.
Since the expression  is NEVER true (note: remember, the absolute value of any number is always positive), there are no solutions to
Also, notice if we graph  and  (just set each side equal to y and graph), we get:
 Graph of  (red) and  (green)
and we can see that the two graphs never intersect. So there are no solutions.
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Trigonometry-basics/252614: Can you help me solve this questions, please?
The original ferris wheel, designed by George Ferris, was 250 feet in diameter. Making 1 revolution for every 40 seconds, h(t)=125sin(0.157t -pi/2) +125 represents the height h (feet) of a seat on the wheel at any time t (seconds). The ride begins when t = 0. During the first 30 seconds of the ride, at what time is a rider on the ferris wheel exactly 125 feet above the ground?
and also, help me with:
approximate the solution to 2cosx+x=0 to the nearest hundredth.
Hints: it should be in radian mode and there are no () around the x+x
Thanks so much!! 1 solutions
Answer 184639 by jim_thompson5910(28595) on 2009-12-29 19:07:33 (Show Source):
You can put this solution on YOUR website! Start with the given equation.
 Plug in
 Subtract 125 from both sides.
 Combine like terms.
 Divide both sides by 125.
 Reduce.
 Rearrange the equation
 Take the arcsine of both sides.
 or  Evaluate the arcsine of 0 to get  or  . Don't forget to add in integer multiples of
---------------------------Side Note----------------------
Take note how if  , then we just get 0 or  . If  , then we get  or  . If we continue this, we can see that we'll hit all of the integer multiples of  . Because of this we can condense the right side to just  .
--------------------------------------------------------
 Condense the right side (see side note above).
 Add  to both sides.
 Combine like terms.
 Multiply both sides by  to isolate 't'.
 Multiply.
Now let's plug in some values of 'n'. If n=0, then
If n=1, then  . However, since we're only worried about the first 30 seconds, this means that  which would exclude the 't' value when  . Any other value of 'n' will generate a 't' value outside the interval
=====================================
Answer:
So the only solution is  (which is approximate) which means that at about 10.00507 seconds, the rider will be 125 feet above the ground during the first 30 seconds.
===========================================================================
# 2
Since the variable we want to solve for in  is buried in a trig function and is outside the trig function, there is no way to solve for it exactly.
So we have to use a graphing calculator to approximate the roots of  . Graphing the given expression, we get
Graph of
Now use the graphing calculator's root/zero function to find the approximate root of  which rounds to  to the nearest hundredth.
So the answer is
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Graphs/252617: using the graph, determine the value of y when x=4
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y 1 solutions
Answer 184638 by jim_thompson5910(28595) on 2009-12-29 18:44:56 (Show Source):
You can put this solution on YOUR website!It's hard to determine which points that line goes through. Do you have a better picture? Or can you tell me which points the graph goes through?
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Numbers_Word_Problems/252619: I am checking my sons math.
Find four consecutive even integers such that 6 time the sum of the first and second is 8 more than 10 times the fourth.
Rob Dewey...Mitchell's Dad. 1 solutions
Answer 184637 by jim_thompson5910(28595) on 2009-12-29 18:43:55 (Show Source):
You can put this solution on YOUR website!Consecutive even integers follow the form: x, x+2, x+4, x+6, etc...
So because "6 time the sum of the first and second is 8 more than 10 times the fourth", this translates to
 Start with the given equation.
 Distribute.
 Combine like terms on the left side.
 Combine like terms on the right side.
 Subtract  from both sides.
 Subtract  from both sides.
 Combine like terms on the left side.
 Combine like terms on the right side.
 Divide both sides by  to isolate  .
 Reduce.
----------------------------------------------------------------------
Answer:
So the solution is  which means that the four consecutive even integers are
x = 28
x+2 = 30
x+4 = 32
x+6 = 34
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Trigonometry-basics/252605: The height of the ocean at the dock is modeled by the function, h= 3sin(pi*t/4) +5 where h is measured in feet and t is the time in hours. If t=0 refers to 12:00 a.m., what is the height of the ocean at 10:00 a.m.?
find the exact value of the vertical asymptotes for 0<=x<=pi for the function y=cot(3x)
if sin(x)= -3/5 with x in the quadrant 4, find the sec(x)
Thanks so much!! 1 solutions
Answer 184615 by jim_thompson5910(28595) on 2009-12-29 16:47:52 (Show Source):
You can put this solution on YOUR website!I'll do the first two to get you going.
# 1
Since "t=0 refers to 12:00 a.m", this means that  refers to 10:00 a.m. (just add 10 hours to 0)
 Start with the given equation.
 Plug in
 Reduce.
 Rearrange the terms
 Subtract  from the argument (this is valid because you'll end up on a coterminal angle).
 Combine like terms.
 Use the unit circle to evaluate the sine of  to get 1.
 Multiply
 Add
So the height of the ocean at 10:00 a.m. is 8 feet.
=================================================================
# 2
Remember that  and  . So this means that  or in short,
To find the vertical asymptotes of  , we'll set the denominator equal to zero and solve for 'x' (since division by zero is undefined).
 Set the denominator equal to zero.
 Take the arcsine of both sides.
 or  Evaluate the arcsine of 0 to get  or  . Don't forget to add on multiples of  to each solution.
 or  Divide both sides by 3 to isolate 'x' in each case.
As a shortcut, you can condense the solution to  where 'n' is an integer.
So if  , where 'n' is an integer, then  .
But since  , this means that we're only going to look at the solutions  (for n=0),  (where n=1),  (when n=2), and  (when x=3). Note: any other solution is outside the interval  .
So the four vertical asymptotes of  are  ,  ,  , and
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Linear-systems/252604: There are 35 tickets to be sold for the dance. The number of tickets sold to seniors must be four times the number of tickets sold to juniors.
please give me 2 linear equations and a solution.
A diamond today costs 10$ more than twice what it cost last year. The sum of the cost (last year and this year) is 2500$. What is the cost of last years diamond?
i need 2 linear equations and a solution for this question also.
THANK U SO MUCH!
1 solutions
Answer 184609 by jim_thompson5910(28595) on 2009-12-29 16:24:26 (Show Source):
You can put this solution on YOUR website!# 1
Let s = # of senior tickets and j = # of junior tickets
Since there are 35 tickets in total, and we're assuming that only junior and senior tickets are sold, this means that  . In other words, adding up the two totals will give you the grand total of 35.
Also, because "The number of tickets sold to seniors must be four times the number of tickets sold to juniors", we know that  . In English, the number of senior tickets 's' is 4 times the number of junior tickets 'j'.
 Start with the first equation.
 Plug in
 Combine like terms on the left side.
 Divide both sides by  to isolate  .
 Reduce.
So there are 7 junior tickets.
 Go back to the second equation
 Plug in
 Multiply
So there are 28 senior tickets.
As a check, take note that 28 is indeed 4 times 7 AND 28+7=35. So we've met our conditions.
======================================================================
# 2
Let t = cost of diamond today and y = cost of diamond last year
Since "A diamond today costs 10$ more than twice what it cost last year", we can say that  (ie double the cost from last year 'y' and add 10 to get the new cost today 't').
Also, because "The sum of the cost (last year and this year) is 2500$", we know that  (just add up the two individual costs to get the grand total of $2500)
 Start with the second equation.
 Plug in
 Combine like terms on the left side.
 Subtract  from both sides.
 Combine like terms on the right side.
 Divide both sides by  to isolate  .
 Reduce.
So the cost of the diamond last year was $830.
If you want to keep going then...
 Go back to the first equation
 Plug in
 Multiply
 Add
So the cost of the diamond today is $1670.
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Linear-systems/252597: Solve the following system of equations algebraically:
3x+2y=4
4x+3y=7 1 solutions
Answer 184601 by jim_thompson5910(28595) on 2009-12-29 15:58:03 (Show Source):
You can put this solution on YOUR website!
Start with the given system of equations:
 Multiply the both sides of the first equation by 3.
 Distribute and multiply.
 Multiply the both sides of the second equation by -2.
 Distribute and multiply.
So we have the new system of equations:
Now add the equations together. You can do this by simply adding the two left sides and the two right sides separately like this:
 Group like terms.
 Combine like terms.
 Simplify.
------------------------------------------------------------------
 Now go back to the first equation.
 Plug in  .
 Multiply.
 Add  to both sides.
 Combine like terms on the right side.
 Divide both sides by  to isolate  .
 Reduce.
So the solutions are  and  .
Which form the ordered pair ) .
This means that the system is consistent and independent.
Notice when we graph the equations, we see that they intersect at ) . So this visually verifies our answer.
 Graph of  (red) and  (green)
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