Factor this polynomial completely.
x^2-81

a=x and b=9

(x+9)(x−9)

Explanation:

Since both terms are perfect squares, factor using the difference of squares formula, a2−b2=(a+b)(a−b)

circle area = pi * radius^2

if diameter = 10 then radius = 5

circle area = pi * 5^2

circle area = pi * 25

circle area = 78.5398163397 square units

step-by-step explanation:

i think it might be a but you might want a second opinion