Question 284612
area of a circle is equal to pi*r^2.


if the area of a circle is also equal to pi * (2x^2 + 16x + 7), this means that:


pi*r^2 = pi*(2x^2 + 16x + 7).


divide both sides of this equation by pi and you get:


r^2 = (2x^2 + 16x + 7)


take the square root of both sides of this equation and you get:


r = +/- sqrt(2x^2 + 16x + 7)