SOLUTION: PLEASE HELP ME!!! question: The area of a circle is given by A = pi(4x^2 + 12x + 9. Find the expression for the radius of the circle. H_E_L_P!!!

Algebra ->  Distributive-associative-commutative-properties -> SOLUTION: PLEASE HELP ME!!! question: The area of a circle is given by A = pi(4x^2 + 12x + 9. Find the expression for the radius of the circle. H_E_L_P!!!      Log On


   

Question 76361: PLEASE HELP ME!!!
question: The area of a circle is given by A = pi(4x^2 + 12x + 9. Find the expression for the radius of the circle.
H_E_L_P!!!
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
The area of a circle is given by:
A+=+%28pi%29%284x%5E2%2B12x%2B9%29
As you probably know,the formula for the area of a circle is:
A+=+%28pi%29r%5E2
Set these two equal to each other:
%28pi%29r%5E2+=+%28pi%29%284x%5E2%2B12x%2B9%29 Divide both sides by %28pi%29
r%5E2+=+4x%5E2%2B12x%2B9 Now factor the right-hand side.
r%5E2+=+%282x%2B3%29%5E2 Take the square root of both sides.
r+=+2x%2B3