Question

You toss a pebble into a pool of water and watch the circular ripples radiate outward. you find that the function r(x) = 12.5x describes the radius r, in inches, of circle x seconds after it was formed. the function a(x) = πx2 describes the area a of a circle with radius x. find to the nearest whole number.

Answer 1

The area will be given by:
a(x)=πx2
The radius is given by the function r(x)=12.5x
hence the area will be:
a(x)=π(12.5x)²
a(x)=156.25πx^2