Factor by grouping.
-$$x ^ { 3 } + 8 x ^ { 2 } + 5 x + 40$$
A) $\left( x ^ { 2 } + 5 \right) ( x + 8 )$
B) $\left( x ^ { 2 } + 5 \right) ( x - 8 )$
C) $\left( x ^ { 2 } + 5 \right) ( x + 8 x )$
D) $\left( x ^ { 3 } + 5 \right) ( x + 8 )$

Question

Quizplus · Accepted Answer

We can group the first two terms together and the last two terms together and factor out a common factor from each group. 
\begin{align*}
x^3 + 8x^2 + 5x + 40 &= (x^3 + 8x^2) + (5x + 40)\
&= x^2(x+8) + 5(x+8)\
&= (x^2+5)(x+8)
\end{align*}
Therefore, the answer is choice A.

Factor by Grouping x3+8x2+5x+40x ^ { 3 } + 8 x ^ { 2 } + 5 x + 40x3+8x2+5x+40

Factor by Grouping $x ^ { 3 } + 8 x ^ { 2 } + 5 x + 40$