Question

Find the product:
(x+9)(x-9)
a 18
b. -81
C. - 18
d. x-64

Answer 1

Answer: B

Explanation:

Simply using (a-b)(a+b)=a^2-b^2.

Evaluate the power (9^2).

x^2 - 81

Answer 2

x^2 -81

Explanation:

(x+9)(x-9)

FOIL

first x*x = x^2

outer -9x

inner 9x

last -9*9 = -81

Add them together

x^2 -9x+9x -81

Combine like terms

x^2 -81