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nerdybill answered: 6961 problems
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Geometry_proofs/201493: This question is from textbook
two angles are complementary. one angle is 12 degree larger than the other. using two variables x and y, find the size of each angle by solving a system of equations.
1 solutions

Answer 151698 by nerdybill(6963) About Me  on 2009-06-29 02:42:10 (Show Source):
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two angles are complementary. one angle is 12 degree larger than the other. using two variables x and y, find the size of each angle by solving a system of equations.
.
Two angles are complementary if the sum of the two angles equals 90 deg.
.
Let x = one angle
and y = second angle
.
equation 1:
x + y = 90
equation 2:
y = x+12
.
Substitute the value of y from equation 2 into equation 1 and solve for x:
x + y = 90
x + x+12 = 90
2x + 12 = 90
2x = 78
x = 39 degrees
.
Substitute the above into equation 2 and solve for y:
y = x+12
y = 39+12
y = 51 degrees
.
Angles are 39 and 51 degrees.


Travel_Word_Problems/201453: If a parade 2mi long is proceeding at 3 mph, how long will it take a runner, jogging at 6 mph, to travel from the front of the parade to the end of the parade?

1 solutions

Answer 151662 by nerdybill(6963) About Me  on 2009-06-28 17:15:12 (Show Source):
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If a parade 2mi long is proceeding at 3 mph, how long will it take a runner, jogging at 6 mph, to travel from the front of the parade to the end of the parade?
.
Apply the distance formula:
d = rt
where
d is distance
r is rate or speed
t is time
.
Let x = time it takes jogger to get to end of parade
then
3x + 6x = 2
9x = 2
x = 2/9 = 1/3 hours
or
x = 20 minutes


Equations/201411: Find an equation of the the line satisfying the given conditions.
Through (2, 8); perpendicular to 9x + 7y = 74

1 solutions

Answer 151639 by nerdybill(6963) About Me  on 2009-06-28 12:09:25 (Show Source):
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Find an equation of the the line satisfying the given conditions.
Through (2, 8); perpendicular to 9x + 7y = 74
.
First, find the slope of:
9x + 7y = 74
Do this by putting it into the "slope-intercept" form:
7y = -9x + 74
y = (-9/7)x + 74/7
Therefore, slope = -9/7
.
If a line is perpendicular, we need the negative reciprocal of the slope above:
Our new slope is then 7/9
Use the slope (7/9) and the given point (2,8) and plug it into the "point-slope" form:
y-y1 = m(x-x1)
y-8 = 7/9(x-2)
y-8 = 7/9(x) - 14/9
y = 7/9(x) - 14/9 + 8
y = 7/9(x) - 14/9 + 72/9
y = 7/9(x) + 58/9 (slope-intercept form of new line)




Equations/201417: Determine whether the given ordered pair is a solution of the given equation.
(x - 4)^2 + (y + 7)^2 = 45; (1, -1)

1 solutions

Answer 151638 by nerdybill(6963) About Me  on 2009-06-28 12:02:58 (Show Source):
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Determine whether the given ordered pair is a solution of the given equation.
(x - 4)^2 + (y + 7)^2 = 45; (1, -1)
.
Plug in the given ordered pair: (x,y) = (1,-1) into
(x - 4)^2 + (y + 7)^2 = 45
(1 - 4)^2 + (-1 + 7)^2 = 45
(-3)^2 + (6)^2 = 45
9 + 36 = 45
45 = 45 (checks)
.
So, yes, (1,-1) is a solution


Equations/201415: Write an equation in standard form for a line passing through the pair of points.
(2, -2) and (0, 3)

1 solutions

Answer 151635 by nerdybill(6963) About Me  on 2009-06-28 11:49:37 (Show Source):
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Write an equation in standard form for a line passing through the pair of points.
(2, -2) and (0, 3)
.
First, find the slope between the two points:
m (slope) = (y2-y1)/(x2-x1)
m (slope) = (3-(-2))/(0-2)
m (slope) = (3+2)/(0-2)
m (slope) = (5)/(-2)
m (slope) = -5/2
.
Using the slope above and one point (0,3) plug it into the point slope form:
y-y1 = m(x-x1)
y-3 = -5/2(x-0)
y-3 = -5/2(x)
5/2(x) + y - 3 = 0 (this is what they're looking for)



Equations/201419: Find the slope of the line, if it is defined.
Through (-3, -9) and (5, 4)

1 solutions

Answer 151633 by nerdybill(6963) About Me  on 2009-06-28 11:44:51 (Show Source):
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Find the slope of the line, if it is defined.
Through (-3, -9) and (5, 4)
.
m (slope) = (y2-y1)/(x2-x1)
m (slope) = (4-(-9))/(5-(-3))
m (slope) = (4+9)/(5+3)
m (slope) = (13)/(8)
m (slope) = 13/8


Equations/201418: Find the slope of the line, if it is defined.
Through (7, -4) and (3, 8)

1 solutions

Answer 151632 by nerdybill(6963) About Me  on 2009-06-28 11:42:34 (Show Source):
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Find the slope of the line, if it is defined.
Through (7, -4) and (3, 8)
m (slope) = (y2-y1)/(x2-x1)
m (slope) = (8-(-4))/(3-7)
m (slope) = (8+4)/(3-7)
m (slope) = (12)/(-3)
m (slope) = -4


Word_Problems_With_Coins/201395: Maria has $169 in ones,fives, and tens. She has twice as many one-dollar bills as she has five dollar bills, and five more ten-dollar bills than five-dollar bills. How many of each type bill does she have?
1 solutions

Answer 151621 by nerdybill(6963) About Me  on 2009-06-28 09:08:48 (Show Source):
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Maria has $169 in ones,fives, and tens. She has twice as many one-dollar bills as she has five dollar bills, and five more ten-dollar bills than five-dollar bills. How many of each type bill does she have?
.
Let x = number of five dollar bills
then
2x = number of one dollar bills
x+5 = number of ten dollar bills
.
2x + 5x + 10(x+5) = 169
2x + 5x + 10x+50 = 169
17x+50 = 169
17x = 119
x = 7 (number of five dollar bills)
.
One dollar bills:
2x = 2(7) = 14
.
Ten dollar bills:
x+5 = 7+5 = 12


Graphs/201381: Hello! I need a help with ASAP!!!
Problem 1.
In 1920, the record for a certain race was 45.4 sec. In 1990, it was 44.0 sec.
Let R(t)= the record in the race and t= the number of the year since 1920.

a) Find a linear function that the date
b) Use the function in (a) to predict the record in 2003 and in 2006.
c) Find the year when the record will be 43.56 sec

Find a linear function that fits the data.
R(t)= ?? -002-45.4???
What is the predicted record for 2003? 43.74??
What is the predicted record for 2006? 43.68??
In what year will the predicted record be 43.56 sec??

I appreciate this.
Thank you!

1 solutions

Answer 151614 by nerdybill(6963) About Me  on 2009-06-28 03:49:11 (Show Source):
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In 1920, the record for a certain race was 45.4 sec. In 1990, it was 44.0 sec.
Let R(t)= the record in the race and t= the number of the year since 1920.
.
a) Find a linear function that the date
Think of the x-axis representing the year and the y-axis representing the "record-time" in seconds.
The problem, then, really gives you two data points: (remember, since 1920)
1920 we get: (0,45.4)
1990 we get: (70,44)
Slope then is
(y2-y1)/(x2-x1) = (44-45.4)/(70-0) = -1.4/70 = -0.02
.
Using the slope and one (70,44) of the two points substitute it into the "point-slope" form:
y-y1 = m(x-x1)
y-44 = -0.02(x-70)
y = -0.02(x-70) + 44
y = -0.02x + 1.4+44
y = -0.02x + 45.4
Replacing y with R(t) and x with t we get:
R(t) = -0.02t + 45.4
.
b) Use the function in (a) to predict the record in 2003 and in 2006.
For 2003:
t = 2003-1920 = 83
R(t) = -0.02t + 45.4
R(t) = -0.02(83) + 45.4
R(t) = -1.66 + 45.4
R(t) = -1.66 + 45.4
R(t) = 43.74 seconds
.
For 2006:
t = 2006-1920 = 86
R(t) = -0.02t + 45.4
R(t) = -0.02(86) + 45.4
R(t) = -1.66 + 45.4
R(t) = -1.72 + 45.4
R(t) = 43.68 seconds
.
c) Find the year when the record will be 43.56 sec
R(t) = -0.02t + 45.4
43.56 = -0.02t + 45.4
43.56-45.4 = -0.02t
-1.84 = -0.02t
92 = t
Year then = 1920+92 = 2012


Geometry_Word_Problems/201345: A rectangle is 4 times as long as it is wide. A second rectangle is 5 centimeters longer and 2 centimeters wider than the first. The area of the second rectangle is 270 square centimeters greater than the first. What are the demensions of the original rectangle?
1 solutions

Answer 151601 by nerdybill(6963) About Me  on 2009-06-27 19:59:08 (Show Source):
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A rectangle is 4 times as long as it is wide. A second rectangle is 5 centimeters longer and 2 centimeters wider than the first. The area of the second rectangle is 270 square centimeters greater than the first. What are the demensions of the original rectangle?
.
Let w = width of original rectangle
then
4w = length of original rectangle
.
(w+2)(4w+5) = w(4w) + 270 (if you don't see this, write back)
4w^2+5w+8w+10 = 4w^2 + 270
4w^2+13w+10 = 4w^2 + 270
13w+10 = 270
13w = 260
w = 20 cm (width of original rectangle)
.
Length:
4w = 4(20) = 80 cm (length of original rectangle)


Quadratic_Equations/201342: Employees of a discount appliance store receive an additional 20% off of the lowest price on an item. If an employee purchases a dishwasher during a 15% off sale, how much will he pay if the dishwasher originally cost $450?
A. $280.90
B. $287
C. $292.50
D. $306
E. $333.89
Can you show me how do this step by step please,I need to know how to this on my own..Please and thank you
1 solutions

Answer 151559 by nerdybill(6963) About Me  on 2009-06-27 12:15:41 (Show Source):
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Employees of a discount appliance store receive an additional 20% off of the lowest price on an item. If an employee purchases a dishwasher during a 15% off sale, how much will he pay if the dishwasher originally cost $450?
.
Original cost: $450
.
15% off original cost:
450 - .15(450)
= 450(1-.15)
= 450(.85)
= $382.5
.
addition 20% discount for employee:
382.5 - .20(382.5)
= 382.5(1-.20)
= 382.5(.80)
= $306
.
Answer: D


Equations/201324: Find an equation of the line satisfying the given conditions.
Throung (0,5); m=-(2/3)
1 solutions

Answer 151546 by nerdybill(6963) About Me  on 2009-06-27 08:52:49 (Show Source):
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Find an equation of the line satisfying the given conditions.
Through (0,5); m=-(2/3)
.
Plug into the "point-slope" form:
y-y1 = m(x-x1)
.
y-5 = -(2/3)(x-0)
y-5 = -(2/3)x
y = -(2/3)x + 5 (this is what they're looking for)
The above is the "slope-intercept" form.
Where
slope (m) is -(2/3)
and
y-intercept is at (0,5)


Equations/201328: Determine wheather the given ordered pair is a solution of the given equation.
2x-5y=18;(4,2)
1 solutions

Answer 151544 by nerdybill(6963) About Me  on 2009-06-27 08:30:38 (Show Source):
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2x-5y=18;(4,2)
.
An "ordered pair" is denoted as (x,y)
So, in this problem, they are asking if
x were equal to 4
and
y were equal to 2
is that a solution for:
2x-5y=18
.
To check,
Plug the given values back into the equation and check:
2x-5y=18
2(4)-5(2)=18
8-10=18
-2 = 18 (NOT true)
.
Therefore (4,2) is NOT a solution.


Linear-systems/201332: Do lines always intersect?

1 solutions

Answer 151543 by nerdybill(6963) About Me  on 2009-06-27 08:26:42 (Show Source):
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No.
Two lines will not intersect if they are parallel.


Age_Word_Problems/201310: The sum of Richard's age and Ruel's age is 60. Nine years ago, Richard was twice as old as Ruel, then how old is Ruel? (pls. include o how you solved the problem)

1 solutions

Answer 151531 by nerdybill(6963) About Me  on 2009-06-27 02:37:26 (Show Source):
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The sum of Richard's age and Ruel's age is 60. Nine years ago, Richard was twice as old as Ruel, then how old is Ruel?
.
Let x = Ruel's age
and y = Richard's age
.
From:"The sum of Richard's age and Ruel's age is 60." we get:
x + y = 60 (equation 1)
.
From:"Nine years ago, Richard was twice as old as Ruel" we get:
y-9 = 2(x-9) (equation 2)
.
Solve equation 1 for y:
x + y = 60
y = 60 - x
.
Substitute the above back into equation 2 and solve for x:
y-9 = 2(x-9)
60-x -9 = 2(x-9)
51-x = 2x-18
51 = 3x-18
69 = 3x
23 years = x (Ruel's age)


Quadratic_Equations/201306: Could someone help me solve for x: 2x/x+4-1/x-3=0
1 solutions

Answer 151530 by nerdybill(6963) About Me  on 2009-06-27 02:30:15 (Show Source):
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2x%2F%28x%2B4%29-1%2F%28x-3%29=0
.
Multiplying both sides by a common denominator: (x+4)(x-3) we get:
2x%28x-3%29-%28x%2B4%29=0
2x%28x-3%29-x-4=0
2x%5E2-6x-x-4=0
2x%5E2-7x-4=0
%282x%2B1%29%28x-4%29=0
.
x = {-1/2, 4}


Complex_Numbers/201309: 6
_____________
a^-3a-54
+
10
______________
a^+5a-6


Hi we are talking about complex fractions. For some reason I cannot figure it out can you please help me!!! Above is a problem that was given to solve. Will you explain it please?
Thanks
1 solutions

Answer 151526 by nerdybill(6963) About Me  on 2009-06-27 00:41:33 (Show Source):
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I believe you mean: (correct me if I'm wrong)
.
+6%2F%28a%5E2-3a-54%29+%2B+10%2F%28a%5E2%2B5a-6%29
.
Factoring the denominators we get:
+6%2F%28%28a-9%29%28a%2B6%29%29+%2B+10%2F%28%28a%2B6%29%28a-1%29%29
.
Now, find common denominator: (a-9)(a+6)(a-1)
and convert each term to have the same denominator:

.
Combining the two terms:
+%286%28a-1%29+%2B+10%28a-9%29%29%2F%28%28a-9%29%28a%2B6%29%28a-1%29%29
.
+%286a-6+%2B+10a-90%29%2F%28%28a-9%29%28a%2B6%29%28a-1%29%29
+%2816a-96%29%2F%28%28a-9%29%28a%2B6%29%28a-1%29%29
.
Factoring the numerator:
+16%28a-6%29%2F%28%28a-9%29%28a%2B6%29%28a-1%29%29


Graphs/201147: write a system of two equations in two unknowns for each problem. Solve each system by substitution.
Question: Investing her bonus. Donna invested her 33,000 bonus and recieved a total of $970 in interest after one year. If part of the money returned 4% and the remainder 2.25% then how much did she invest at each rate?
1 solutions

Answer 151359 by nerdybill(6963) About Me  on 2009-06-25 10:27:43 (Show Source):
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Investing her bonus. Donna invested her 33,000 bonus and recieved a total of $970 in interest after one year. If part of the money returned 4% and the remainder 2.25% then how much did she invest at each rate?
.
Let x = amount invested at 4%
and y = amount invested at 2.25%
.
From:"Donna invested her 33,000 bonus"
x + y = 33000 (equation 1)
.
From:"a total of $970 in interest after one year"
.04x + .0225y = 970
.
Solving equation 1 for y:
x + y = 33000
y = 33000 -x
.
Substitute the above into equation 2 and solve for x:
.04x + .0225y = 970
.04x + .0225(33000-x) = 970
.04x + 742.5 -.0225x = 970
.04x -.0225x = 227.5
0.0175x = 227.5
x = $13000 (amount invested at 4%)
.
Amount invested at 2.25%
y = 33000 -x = 33000 -13000 = $20000


Geometric_formulas/201138: This question is from textbook geometry
can you please help me solve ((( A rectangular solid with length 8 and width3 has bolume 48. Find its height. )))
1 solutions

Answer 151353 by nerdybill(6963) About Me  on 2009-06-25 09:06:08 (Show Source):
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can you please help me solve ((( A rectangular solid with length 8 and width3 has bolume 48. Find its height. )))
.
Since the volume on any rectangular solid is length*width*height we have:
.
Let h = height
then
8*3*h = 48
24h = 48
h = 2 (height)


Rectangles/201130: A rectangular swimming pool is 2 m longer than it is wide. If the width is decreased by 3 m, and the length is increased by 4 m, the area remains the same as the original area, Find the original dimensions of the pool.
1 solutions

Answer 151352 by nerdybill(6963) About Me  on 2009-06-25 09:03:57 (Show Source):
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A rectangular swimming pool is 2 m longer than it is wide. If the width is decreased by 3 m, and the length is increased by 4 m, the area remains the same as the original area, Find the original dimensions of the pool.
.
Let w = width of pool
then
w+2 = length of pool
.
(w-3)(w+2 +4) = w(w+2)
(w-3)(w+6) = w(w+2)
w^2+6w-3w-19 = w^2+2w
w^2+3w-19 = w^2+2w
3w-19 = 2w
w-19 = 0
w = 19 m (width of pool)
.
Length:
w+2 = 19+2 = 21 m (length of pool)
.
Dimensions: 19m x 21m


Miscellaneous_Word_Problems/201094: The area fo a rectangle is 66ft squared and the diagonal of the rectangle is square root of 157 ft. What are the dimensions of the rectangle.
1 solutions

Answer 151350 by nerdybill(6963) About Me  on 2009-06-25 07:06:21 (Show Source):
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The area fo a rectangle is 66ft squared and the diagonal of the rectangle is square root of 157 ft. What are the dimensions of the rectangle.
.
Let x = width
and y = length
.
Since we have two unknowns, we'll need two equations:
Equation 1:
xy = 66
Equation 2:
x%5E2+%2B+y%5E2+=+sqrt%28157%29%5E2
x^2 + y^2 = 157
.
Solving equation 1 for y:
y = 66/x
Substituting the above into equation 2 we can solve for x:
x^2 + y^2 = 157
x^2 + (66/x)^2 = 157
x^2 + 4356/x^2 = 157
x^4 + 4356 = 157x^2
x^4 - 157x^2 + 4356 = 0
Factoring we get:
(x^2-121)(x^2-36) = 0
x = {11,6}
.
Dimensions of rectangle are 11 feet by 6 feet


expressions/201017: Rewrite the formula V=1/3BH to solve for h
1 solutions

Answer 151265 by nerdybill(6963) About Me  on 2009-06-24 13:51:19 (Show Source):
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V=1/3BH
Multiplying both sides by 3:
3V=BH
Dividing both sides by B:
3V/B = H


Geometric_formulas/200998: This question is from textbook geometry
can you please help me solve (((Find the volume of a sphere with radius 3cm. Leave answer in terms of pie)))
1 solutions

Answer 151229 by nerdybill(6963) About Me  on 2009-06-24 09:45:27 (Show Source):
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Volume of any sphere:
%284%2F3%29%28pi%29r%5E3
So, if r = 3 cm
then
.
%284%2F3%29%28pi%293%5E3
.
%284%2F3%29%28pi%29%2827%29
.
4%28pi%29%289%29
.
36%28pi%29 cubic cm


Geometric_formulas/201000: This question is from textbook geometry
can you please help me solve (((What is the volume of a cube with edge 2? )))
1 solutions

Answer 151227 by nerdybill(6963) About Me  on 2009-06-24 09:38:54 (Show Source):
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By definition, all sides of a cube are the same.
Therefore, the volume is:
2*2*2 = 8


Linear_Equations_And_Systems_Word_Problems/200947: please help me solve this problem:
a farmer and his son leave a barn at the same time and walk in opposite driections checking a fence line. the son walks at the speed of 3.5km/h and the farmer at 4.0km/h. how much time will have elapsed when the farmer and his son are 2.5km apart
1 solutions

Answer 151187 by nerdybill(6963) About Me  on 2009-06-23 18:15:04 (Show Source):
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a farmer and his son leave a barn at the same time and walk in opposite driections checking a fence line. the son walks at the speed of 3.5km/h and the farmer at 4.0km/h. how much time will have elapsed when the farmer and his son are 2.5km apart
.
Apply the distance formula:
d = rt
where
d is distance
r is rate or speed
t is time
.
Let t = elapsed time
then
3.5t + 4t = 2.5
7.5t = 2.5
t = 2.5/7.5
t = 25/75
t = 1/3 of an hour (or 20 minutes)


Length-and-distance/200920: This question is from textbook Geometry
Given points A (-5,8) and B (3,4)sketch vector AB on the graph provided
1 solutions

Answer 151185 by nerdybill(6963) About Me  on 2009-06-23 18:11:52 (Show Source):
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Plot point (-5,8) on the graph
Plot point (3,4) on the graph
Connect the two points with a solid line
The vector starts at A and ends at B, so draw the arrow head at B.


Square-cubic-other-roots/200950: Simplify sqrt 5 / sqrt 11
1 solutions

Answer 151182 by nerdybill(6963) About Me  on 2009-06-23 18:08:57 (Show Source):
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sqrt%285%29%2F+sqrt%2811%29
.
You have to "rationalize" the fraction -- remove all radicals from the denominator.
.
sqrt%285%29%2F+sqrt%2811%29+%2A+sqrt%2811%29%2F+sqrt%2811%29
.
%28sqrt%2855%29%29%2F+11


Equations/200843: 5.8 + [-log(10^-6)-log(1)-2](2.9)= x
1 solutions

Answer 151097 by nerdybill(6963) About Me  on 2009-06-22 16:07:23 (Show Source):
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5.8 + [-log(10^-6)-log(1)-2](2.9)= x
5.8 + [-(-6)-0-2](2.9)= x
5.8 + [6-0-2](2.9)= x
5.8 + [4](2.9)= x
5.8 + 11.6= x
5.8 + 11.6= x
17.4=x


Geometry_Word_Problems/200841: A circle is tangent to the x-axis and to the y-axis. The coordinates of its center are both positive. The area of the circle is 64pie. What are the coordinates of the point of tangency on the y-axis?
1 solutions

Answer 151065 by nerdybill(6963) About Me  on 2009-06-22 10:26:18 (Show Source):
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A circle is tangent to the x-axis and to the y-axis. The coordinates of its center are both positive. The area of the circle is 64pie. What are the coordinates of the point of tangency on the y-axis?
.
Area of a circle = (pi)r^2
.
They gave us the area as 64(pi)
.
64(pi) = (pi)r^2
64 = r^2
8 = r (radius)
.
Since the coordinates of the center are both positive, we know it is in the 1st quadrant.
.
point tangent on the y-axis is then (0,8)


Miscellaneous_Word_Problems/200817: It takes Steve 3 hrs longer to paint a floor than it takes Paul. When working together, it takes them 2 hours. How long would each take to do the job alone?
1 solutions

Answer 151057 by nerdybill(6963) About Me  on 2009-06-22 08:51:19 (Show Source):
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It takes Steve 3 hrs longer to paint a floor than it takes Paul. When working together, it takes them 2 hours. How long would each take to do the job alone?
.
Let p = time it takes for Paul to paint the floor alone
then
p+3 = time it takes for Steve to paint the floor alone
.
2(1/p + 1/(p+3)) = 1
2/p + 2/(p+3) = 1
2(p+3) + 2p = p(p+3)
2p+ 6 + 2p = p^2+3p
8p+ 6 = p^2+3p
6 = p^2-5p
0 = p^2-5p-6
0 = (p-6)(p+1)
p = {6, -1}
We throw out the negative solution leaving us with:
p = 6 hours (time it takes Paul)
.
Steve:
p+3 = 6+3 = 9 hours (time it takes Steve)


Linear-systems/200813: get the value of x and y
x-y=5
3x+y=3
1 solutions

Answer 151054 by nerdybill(6963) About Me  on 2009-06-22 07:23:41 (Show Source):
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Applying the substitution method:
x-y=5 (equation 1)
3x+y=3 (equation 2)
.
Solve equation 1 for x:
x-y=5
x = y+5
Substitute the above into equation 2 and solve for y:
3x+y=3
3(y+5)+y=3
3y+15+y=3
4y+15=3
4y = -12
y = -3
.
Substitute the above into equation 1 and solve for x:
x-y=5
x-(-3)=5
x+3 = 5
x = 2
.
Solution:
x=2 and y=-3