Factor by grouping.
-$15 x ^ { 4 } + 20 x ^ { 2 } - 12 x ^ { 2 } - 16$
A) $\left( 5 x ^ { 2 } - 4 \right) \left( 3 x ^ { 2 } + 4 \right)$
B) $\left( 5 x ^ { 2 } + 4 \right) \left( 3 x ^ { 2 } - 4 \right)$
C) $\left( 15 x ^ { 2 } + 4 \right) \left( x ^ { 2 } - 4 \right)$
D) $\left( 5 x ^ { 4 } - 4 \right) ( 3 x + 4 )$

Question

Quizplus · Accepted Answer

First, group the terms: $15x^4 + 20x^2$ and $-12x^2 - 16$. Factoring out the greatest common factor from each group gives $5x^2(3x^2 + 4) - 4(3x^2 + 4)$. Factoring by grouping gives $(5x^2 - 4)(3x^2 + 4)$.

Factor by Grouping 15x4+20x2−12x2−1615 x ^ { 4 } + 20 x ^ { 2 } - 12 x ^ { 2 } - 1615x4+20x2−12x2−16

Factor by Grouping $15 x ^ { 4 } + 20 x ^ { 2 } - 12 x ^ { 2 } - 16$