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Question 233885: I have a question regarding a previous question that was answered. It's under question #144072:

Q:Solve by factoring.
The radius of a circle is increased by 3 in., which increases the area by 100 in^2. Find the radius of the original circle. Round to the nearest hundredth.
Please answer.This question is from textbook Beginning Algebra with Applications

The answer was given as:
1. pi*r^2=A original
(this is clear)
2. pi*(r+3)^2=A+100 new
(this is clear)
3. pi(r^2+6r+9)=A+100
(this is clear)
4. pi(r^2+6r+9)-100=A
(this is clear)
5. pi(r^2+6r+9)-100=pi*r^2
(please explain this step? I don't understand how the transition took place from moving the "pi" from the front to placing it behind the 100 in the parentheses)? Please write out the step?
6. r^2+6r+9-(100/pi)=r^2

(this is clear)
7. 6r+9-31.83=0
(this is clear)
8. 6r=22.83
(this is clear)
9. r=3.81

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Question 233984: solve ( x+3 )( x-5 )
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Question 234003: Use the quadratic formula to determine the x-intercepts (if any) of the following function
f(x) = 3x2
i can grapg this buy substituting a number for x and that would give me y. but if i use that quadratic formula i need an a,b,c and i only have an a. therfore i believe that i cant get the x intersepts by using the quadratic formula what di you think
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Question 234010: 2s+9sw-35w^2=
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Question 234012: Use the quadratic formula to determine the x-intercepts (if any) of the following function. Then evaluate the function for several values of x, and use the resulting points to graph the function
f(x) = 3x2
ok i figured out that by using the qaudratic formula my answer is x=0
so i guess how do figure out my x intercepts and how do i come up with other points so that i can graph this.
Click here to see answer by scott8148(6628)

Question 234186: I need to use the discriminant to determine the number of solutions of the quadratic equation, and whether the solutions are real or complex. (it is not necessary to find the roots; just determine the number and types of solutions)
x^2 + 6x - 7 = 0
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Question 234184: For this problem I need to complete the square, and find the roots of the quadratic equation
x^2 + 16x = 0
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Question 234184: For this problem I need to complete the square, and find the roots of the quadratic equation
x^2 + 16x = 0
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Question 234141: Consider the Quadratic formula f(x)=x^2-2x-35
What is the vertex?
x-intercepts
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Question 234231: how would i solve x²-8x=0 by factoring?
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Question 234272: I am stumped on these equations. I have to solve them with the following steps:
a) Move the constant term to the right side of the equation.
b) Multiply each term in the equation by four times the coefficient of the x squared term.
c) Square the coefficient of the original x term and add it to both sides of the equation.
d) Take the square root of both sides.
e) Set the left side of the equation to the positive square root of the right side and solve for x.
f) Set the left side of the equation equal to the negative square root of the right side and solve for x.
The equations I am stumped on are:
x^2+12x-64
2x^2-3x-5=0
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Question 234378: how do you solve this equations m4+7m3+12m2=0
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Question 234392: A student took out two loans totaling $10,000 to help pay for college expenses. One loan was at 8% simple interest, and the other was at 10%. After one year, the student owed $840 in interest. Find the amount of the loan at 10%.

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Question 234374: how would i solve this quadratic equation? { { { 4x^2=48 } } }
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Question 234417: find the maximum value:
f(x)= -10/3(x+5)^2-5
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Question 234381: What is a step-by-step way to solve a Quadratic Equation?
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Question 234421: use 4.9t^2 + vot = s

a coin is tossed downward with an initial velocity of 30 meters per second(v0)at an altitude of 402 meters(s). approximetly how long does it take the coin to reach the ground?
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Question 234430: 2 different rational solutions, 2 different irrational solutions,exactly one rational solution or 2 different imaginary solutions??
x^2 - 12x + 34 = 0
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Question 234434: translate the problem into a pair linear equations in two variables.solve using elimination or substitution.
andy has 14 coins made up of quarters and half dollars, and their total value is $4.25.How many quarters does he have?

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Question 234414: solve by using the quadratic equation:
x^2 + 8x = 3
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Question 234505: investment of 4000 in 3 months with interest of 6.1 what was the earned amount?
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Question 234418: How to find an equation of a line that is intercepting the two parabolas?
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Question 234369: Hi
Need Help with this Question
Gerald hit his golfball down the fairway. The path the ball followed was parabolic in the shape with the relationship:
h=2d-1/30^2
Where h is the height above the ground of the golf ball when it is a horizontal distance d from him. Both h and d are in meters. How far from Gerald did the golf ball land?
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Question 234676: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
3x^2+2x-4=0
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Question 234683: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
2x^2+x-6=0
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Question 234682: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
4x^2-5x=0
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Question 234681: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
7x^2+4x=5
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Question 234680: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
3x^2-5x=2
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Question 234678: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
2x^2+4x=1
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Question 234677: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
5x^2+2x-3=0
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Question 234674: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
x^2-3x-5=0
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Question 234673: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
x^2-7x=-3
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Question 234671: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
x^2-5=2x
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Question 234670: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
x^2+5x=7
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Question 234668: Use the quadratic formula to solve equation. Write irrational roots in the simplest radical form.
x^2+2x=4
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Question 234703: 1. The teacher put sets of paints into different-sized boxes. She labeled the boxes to show how many sets were in each one. The boxes were labeled 32, 15, 17, 16, 19 and 21. The teacher needed 50 sets of paints. Which three boxes should she choose?
PLEASE ANSWER THE QUESTIONS BECAUSE I DONT GET IT THANK YOU VERY MUCH!!!!
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Question 234861: I have the hardest time with word problems. For this problem I need to use the discriminate to determine the number of solutions of the quadratic equation, and whether the solutions are real or complex. It is not necessary to find the roots; just determine the number and types of solutions.

The hudson river flows at a rate of 3 miles per hour. A patrol boat travels 60 miles upriver, and returns in a total time of 9 hours. What is the speed of the boat in still water?
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Question 234900: There are three ways for solutions to exist.
1.No Solutions
2.One Solution
3.Two Solutions
Please find the number of solution for the following equation based on your response to the above statement.
x^2 - 3x + 2 = 0.
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Question 234912: (x+2)^2-3 in standard form
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Question 234938: This problem I must factor the quadratic expression completely, and find the roots of the expression.

6x^2 - 42x + 72
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Question 234937: This problem I must factor the quadratic expression completely, and find the roots of the expression.
135x^2 - 222x + 91
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Question 234936: For this problem I must apply the quadratic formula to find the roots of the given function and then graph the function.

g(x)=x^2+x+12
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Question 234935: For this problem I must apply the quadratic formula to find the roots of the given function and then graph the function.
f(x)=x^2+4
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Question 234944: For this problem I must complete the square, and find the roots of the quadratic equation.
x^2 - 2/3x = 0
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