which of the following expressions is equivalent to (13+2) (13-2) ?

Question

a) 15² + 11²

b) 15² - 11²

c) 13² + 2²

d) 13² - 2²

Answer 1

d) 13^2 -2^2

(13+2)(13-2) = 13^2 -2^2 = 169-4 = 165

(13+2)(13-2) = 15(11) = 165

this is a specific example of a general algebraic expansion

(a-b)(a+b) = a^2-b^2, where a=13 and b=2