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rapaljer answered: 4664 problems
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Answer 166237 by rapaljer(4667) on 2009-10-05 02:12:26 (Show Source):
You can put this solution on YOUR website!Let x = smaller integer
x+2 = second odd integer (larger)
7x- 2(x+2) =201
7x -2x-4 =201
5x =201+4
5x=205
x=41 smaller
x+2 = 43 larger
Check: 7*41 - 2*43 = 201??
287-86=201 Yes! It checks!!
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Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
Altamonte Springs Campus
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Surface-area/221718: Find the area of the shaded area in the following figure if the rectangle inscribed in the circle has dimensions 8ft x 6ft
1 solutions
Answer 166236 by rapaljer(4667) on 2009-10-05 01:57:13 (Show Source):
You can put this solution on YOUR website!I can't "see" your picture, so I don't know what part of this is shaded. However, the rectangle inscribed inside the circle is 6 by 8, with center at the center of the circle. The diagonal of the rectangle will be the same as the diameter of the circle. By Theorem of Pythagoras, 6^2 + 8^2 = d^2, so d is 10. Therefore the radius of the circle is 5 feet.
As I said, I don't know what area is shaded, but the area of the circle is
 sq. ft.
The area of the rectangle is A=LW= 48 sq. ft.
You probably have to subtract the areas to get the shaded area. My guess is that the area is  sq. ft.
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Dr. Robert J. Rapalje, Retired
Seminole State College
Altamonte Springs Campus.
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Quadratic_Equations/221721: A ball is thrown vertically upward from the Leaning Tower of Pisa (176 feet high)with an initial velocity of 96 feet per second. The height of the ball is described by the formula -16t^2 + 96t +176. How long will it take the ball to hit the ground?
Please help I have tried to solve this several different ways and none of them are coming out to anything that makes sense. The example in the textbook shows it starting to be solved by factoring out -16 , but I can't see were it can go from there? 1 solutions
Answer 166233 by rapaljer(4667) on 2009-10-05 01:38:26 (Show Source):
You can put this solution on YOUR website!When the ball hits the ground, h=0, so set the equation equal to zero.
-16t^2 + 96t +176=0
-16(t^2 - 6t - 11)=0
What results here is a quadratic equation that cannot be factored. You will have to use the quadratic formula or completing the square. It turns out that completing the square is easier for this problem.
t^2 -6t -11=0
t^2 -6t +_____= 11+_____
Take HALF of the coefficient of t, which is -6 and SQUARE it. Half of -6 would be -3, and -3 squared is +9. Add =9 to each side:
t^2 -6t+9 = 11+9
(t-3)^2 = 20
Now you can take square root of each side like this:
Then add +3 to each side:
Reject the negative value since time cannot be negative.
Finally, either calculate this, or simplify the square root. By approximation (my calculator is in the other room!) square root of 20 is about 4.5, so the time is about 3+4.5= 7.5 seconds--very approximately!!
The exact value is this:
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Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
Altamone Springs Campus
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real-numbers/221722: how to break down irrational numbers by using perfect squares example:the square root of 44 1 solutions
Answer 166232 by rapaljer(4667) on 2009-10-05 01:22:43 (Show Source):
You can put this solution on YOUR website!To simplify square root numbers like  , you need to find a perfect square that is a factor of 44. This would be 4. By the Product Property of Square Roots, you can write this:
For additional explanation on SQUARE ROOTS, please see my own website. Use the easy-to-remember and easy-to-spell link www.mathinlivingcolor.com. Click on the link near the bottom of this page, which will take you to my Homepage. On my Homepage near the top, look for the link "Basic, Intermediate and College Algebra: One Step at a Time." Choose "Basic Algebra", and look in Chapter 5 for sevearl topics on SQUARE ROOTS. For help with this type of problem, look in my Section 5.01. In these sections, you will find my own non-traditional explanations, that my own students all said were a LOT easier to understand than traditional textbooks. See also the corresponding "MATH IN LIVING COLOR" pages in which problems are solved IN COLOR! I also have FREE videos on the website of me teaching my classes a few years ago. To access the videos, go back to my Homepage, and look for the link "Rapalje Videos in Living Color." Select "Basic Algebra", and select the video on "Radicals (Square Roots)."
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Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
Altamonte Springs Campus
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Travel_Word_Problems/221740: Avoiding a collision. A car is traveling on a road that
is perpendicular to a railroad track. When the car is
30 meters from the crossing, the car’s new collision
detector warns the driver that there is a train 50 meters
from the car and heading toward the same crossing. How
far is the train from the crossing? 1 solutions
Answer 166230 by rapaljer(4667) on 2009-10-05 01:08:40 (Show Source):
You can put this solution on YOUR website!Let x = distance of the train from the intersection. The distance of the car from the railroad crossing is 30 meters, and the direct distance from the car to the train is 50 meters. Notice that this picture (if you can see it!) is a right triangle, with the hypotenuse = 50 meters, the legs being x and 30.
By the Theorem of Pythagoras, a^2 + b^2 = c^2, where c is the hypotenuse.
x^2 + 30^2 = 50^2
x^2 + 900=2500
x^2 = 1600
Take sthe square root of each side:
Reject negative answer,
 meters.
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Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
Altamone Springs Campus
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Equations/221738: 9(K-4)+2K=2(K-1)=7K
1 solutions
Answer 166229 by rapaljer(4667) on 2009-10-05 01:01:47 (Show Source):
You can put this solution on YOUR website!I think you mis-typed this equation. You have TWO equal signs. Why don't you correct and re-post. Or if you are not in a hurry for this, send me an Email, and if I'll try to get it to you next time I'm available.
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Polynomials-and-rational-expressions/221726: I need to factor this expression completely.
27y^5 - 63y^4 + 30y^3 1 solutions
Answer 166228 by rapaljer(4667) on 2009-10-05 00:58:04 (Show Source):
You can put this solution on YOUR website!The first step is ALWAYS to take out the common factor if there is one. In this case, the common factor to each term is 3 y^3.
27y^5 - 63y^4 + 30y^3
3y^3(9y^2 - 21y + 10)
What is left is what I call "Advanced Trinomial Factoring", where the leading coefficient of the trinomial is other than 1. I use a trial and error method.
It could be one of the following possibilities to give you the 9y^2 in the FIRST times FIRST term:
3y^3(3y_____)(3y______) or 3y^3(9y_____)(y_____)
Next, you need to find two numbers whose product is 10. This is probably 5*2, but it could also be 10*1. Let's try the 5*2 combination first:
3y^3(3y_____)(3y______)
3y^3(3y-5)(3y-2)
This one works, since the LAST times LAST is +10, and the MIDDLE TERM will be -6y -15y, which is -21y. It checks!
For additional explanation on Factoring, especially COMMON FACTOR and ADVANCED TRINOMIAL FACTORING, please see my own website. Do a "Bing" search for my last name "Rapalje". Look for "Rapalje Homepage" near the top of the search list. On my Homepage near the top, look for the link "Basic, Intermediate and College Algebra: One Step at a Time." Choose "Basic Algebra", and look in Chapter 2 for sevearl topics on FACTORING. In these sections, you will find my own non-traditional explanations, that my own students all said were a LOT easier to understand than traditional textbooks. See also the corresponding "MATH IN LIVING COLOR" pages in which problems are solved IN COLOR! I also have FREE videos on the website of me teaching my classes a few years ago. To access the videos, go back to my Homepage, and look for the link "Rapalje Videos in Living Color." Select "Basic Algebra", and select the video on "FACTORING."
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Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
Altamonte Springs Campus
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Linear_Equations_And_Systems_Word_Problems/221732: In what fundamental way does the solution set of a system of linear equations differ from the solution set of a system of linear inequalities? Give examples, please
1 solutions
Answer 166227 by rapaljer(4667) on 2009-10-05 00:38:51 (Show Source):
You can put this solution on YOUR website!The solution set for a set of linear equations is usually a single point, but it may also be an entire line or NO SOLUTION. The solution set for a set of linear inequalities is usually a shaded region in the coordinate plane. In extreme cases, it could possibly be NO SOLUTION or an entire line.
You can think of the examples!!
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Complex_Numbers/221736: find the complex number a + bi such that 5a + 3b = 1 and -5a = 7 + 4a 1 solutions
Answer 166224 by rapaljer(4667) on 2009-10-05 00:27:43 (Show Source):
You can put this solution on YOUR website!5a + 3b = 1 and -5a = 7 + 4a
From the second equation,
-9a=7
a=-7/9
Back into the first equation:
5a+3b=1
5(-7/9)+3b=1
-35/9 +3b=1
-35/9+35/9+3b=1+35/9
3b=9/9+35/9
3b=44/9
b=44/27
Check me out to see if I have any "math" errors here. There isn't a handy way to check this without essentially re-working it. Sorry about that!!
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Dr. Robert J. Rapalje
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Travel_Word_Problems/221733: if you row 360 feet against the current in 6 minutes and 500 feet with the current in 5 minutes how fast is the current? 1 solutions
Answer 166223 by rapaljer(4667) on 2009-10-05 00:19:30 (Show Source):
You can put this solution on YOUR website!Let x= speed in still water
c= speed of current
Rate = Dist/Time
x+c = rate with the stream= 500 feet/5 min
x-c= rate against the stream=360 feet/6 min
x+c=100
x-c=60
Add the equations together:
2x=160
x=80 ft/min= speed in still water
x+c=100
80+c=100
c=20 ft/min= speed of current
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Dr. Robert J. Rapalje
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Square-cubic-other-roots/221427: (ax+by)^2 +(bx-ay)^2 1 solutions
Answer 166074 by rapaljer(4667) on 2009-10-04 15:25:14 (Show Source):
You can put this solution on YOUR website!(ax+by)^2 +(bx-ay)^2
(a^2x^2 + 2abxy + b^2y^2) + (b^2x^2 -2abxy + a^2y^2)
a^2x^2 + b^2y^2 + b^2x^2 + a^2y^2
Did you want to factor this? If so, do factoring by grouping:
a^2x^2 + b^2x^2 + b^2y^2 + a^2y^2
x^2(a^2 +b^2) + y^2(a^2 + b^2)
(a^2 + b^2) (x^2+y^2)
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Dr. Robert J. Rapalje
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Polynomials-and-rational-expressions/221425: what is the horizontal asymptote(s) of -10(x-7)^5(x+8)^4/x^9-15x^5+56? 1 solutions
Answer 166073 by rapaljer(4667) on 2009-10-04 15:19:44 (Show Source):
You can put this solution on YOUR website!Notice that the degree of the numerator is 9 and the degree of the denominator is also 9. Send me an Email if you need additional explanation of this!
If the degrees of the numerator and denominator are the same, then there is a horizontal asymptote at y = (ratio of the leading coefficients of the numerator and denominator. In this case, it will be y=-10/1=-10.
Horizontal asymptote at y =-10.
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Dr. Robert J. Rapalje
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absolute-value/221280: negative 3 times the absolute value of 2 times a number minus 5 equals 15 1 solutions
Answer 165997 by rapaljer(4667) on 2009-10-04 09:38:24 (Show Source):
You can put this solution on YOUR website!If this is what you meant -3|2x-5|=15, then divide both sides by -3, and you get |2x-5|= -5. There is NO SOLUTION since an absolute value cannot equal a negative number.
If you meant -3|2x|-5 = 15, then you begin by adding +5 to each side.
-3|2x| = 20. Next, divide by -3, and you get the same result: absolute value cannot equal a negative number.
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Equations/221220: S=(a-rl)/(1-r) solve for l we get l=(a-S-Sr)/r Bagatrix solver tells us the Sr should be positive, what step did we miss or mess up on. 1 solutions
Answer 165978 by rapaljer(4667) on 2009-10-03 23:51:23 (Show Source):
You can put this solution on YOUR website!S=(a-rl)/(1-r)
Multiply both sides by 1-r:
S(1-r) = a-rl
S-Sr=a-rl
I would add +rl to each side:
S-Sr+rl =a
Then I would subtract S and add +Sr to each side:
rl=a -S +Sr
Divide both sides by r:
l=(a-S+Sr)/r
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Miscellaneous_Word_Problems/221198: A rectangular counter is being built for the customer service department of a store. Designers have determined that the outside perimeter of the counter needs to exceed 30 feet. Determine the acceptable values for X.
(X+5)FT
X FT 1 solutions
Answer 165971 by rapaljer(4667) on 2009-10-03 23:38:58 (Show Source):
You can put this solution on YOUR website!2x+2(x+5)>30
2x+2x+10>30
4x+10>30
4x>20
x>5
x+5>10
The width must be greater than 5 ft, which makes the length greater than 10 ft.
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Complex_Numbers/221155: I have an equation (2x^2)-7=0. The answer I have been given is the square root of 14 over 2. I'm unsure why. Could you walk me through the steps please? 1 solutions
Answer 165947 by rapaljer(4667) on 2009-10-03 22:03:54 (Show Source):
You can put this solution on YOUR website!2x^2 -7=0
2x^2 =7
x^2=7/2
The trick now is to rationalize the denominator, by multiplying numerator and denominator by square root of 2:
 *
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Equations/221048: I need help on this word problem setting up the equation. A 2000L tank containing 550L of water is being filled with water at the rate of 75L per minute from a full 1600L tank. How long will it be before the two tanks have the same amount of water? X equals time. Not sure how to set up this equation and solve. 1 solutions
Answer 165846 by rapaljer(4667) on 2009-10-03 15:40:32 (Show Source):
You can put this solution on YOUR website!Let x = number of minutes
75 x = amount of water transferred
1600-75x = amount of water in the larger tank after x minutes draining
550 + 75x = amount of water in the tank being filled after x minutes of filling
1600-75x = 550 + 75x
Add +75x to each side.
1600=550 + 75x+75x
Subtract 550 from each side:
1050= 150x
Divide by 150
7=x
Final Answer = 7 minutes.
Check: After 7 minutes, 7*75 = 525 gallons of water transferred
550+525 = 1075 gallons in first tank
1600-525 = 1075 gallons in second tank
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Dr. Robert J. Rapalje
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