Factor the polynomial completely. $4 - 81 y ^ { 2 }$
A) (2 $-$ 81 y ) (2 + 81 y )
B) (2 $-$ 9 y ) (2 + 9 y )
C) (4 $-$ 9 y ) (4 + 9 y )
D) (2 + y ) (2 + 9 y )
E) none of these

Question

Quizplus · Accepted Answer

This is a difference of squares, so we can use the formula $(a^2-b^2)=(a+b)(a-b)$ with $a=2$ and $b=9y$ to get $(2-9y)(2+9y)=\boxed{\textbf{(B)}\ (2-9y)(2+9y)}$.

Factor the Polynomial Completely 4−81y24 - 81 y ^ { 2 }4−81y2

Factor the Polynomial Completely $4 - 81 y ^ { 2 }$