Factor completely. Check by multiplying the factors. $25 b ^ { 2 } - 16$
A) $( 8 b - 4 ) ( 8 b + 4 )$
B) $( 25 b - 4 ) ( b + 4 )$
C) $( 6 b - 4 ) ( 6 b + 4 )$
D) $( 5 b - 4 ) ( 5 b + 4 )$
E) $( 5 b + 4 ) ( 5 b + 4 )$

Question

Quizplus · Accepted Answer

This is a difference of squares, which factors into $(5b-4)(5b+4)$. To check, we can use FOIL: $$(5b-4)(5b+4) = (5b)^2 + (5b)(4) - (4)(5b) - (4)(4) = 25b^2 - 16$$ Therefore, choice D is the correct factorization.

Factor Completely 25b2−1625 b ^ { 2 } - 1625b2−16 A) (8b−4)(8b+4)( 8 b - 4 ) ( 8 b + 4 )(8b−4)(8b+4)

Factor Completely $25 b ^ { 2 } - 16$ A) $( 8 b - 4 ) ( 8 b + 4 )$