Factor.
-$$x ^ { 2 } + 2 x y - 8 y ^ { 2 }$$
A) $( x + 4 y ) ( x - 2 y )$
B) $( x - 4 y ) ( x + y )$
C) $( x - y ) ( x + 2 y )$
D) $( x - 4 y ) ( x + 2 y )$

Question

Quizplus · Accepted Answer

The correct factorization is obtained by finding two numbers that multiply to $ac$ (where $a$ is the coefficient of $x^2$ and $c$ is the constant term, here $ac = -8$) and add to $b$ (the coefficient of $xy$, here $b = 2$). The numbers $4$ and $-2$ work, leading to the factorization $(x + 4y)(x - 2y)$.

Factor - x2+2xy−8y2x ^ { 2 } + 2 x y - 8 y ^ { 2 }x2+2xy−8y2

Factor
- $x ^ { 2 } + 2 x y - 8 y ^ { 2 }$