If $f ( x ) = 2 x ^ { 2 } - 4 x - 7$ , find $f ( c + 5 )$.
A) $2 c ^ { 2 } - 4 c + 23$
B) $2 c ^ { 2 } + 16 c + 63$
C) none of these
D) $2 c ^ { 2 } + 16 c + 23$

Name: If $f ( x ) = 2 x ^ { 2 } - 4 x - 7$ , find $f ( c + 5 )$. A) $2 c ^ { 2 } - 4 c + 23$ B) $2 c ^ { 2 } + 16 c + 63$ C) none of these D) $2 c ^ { 2 } + 16 c + 23$
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Question

Quizplus · Accepted Answer

Substitute $c+5$ for $x$ in the expression for $f(x)$:
\begin{align*}
f(c+5)&=2(c+5)^2-4(c+5)-7\
&=2(c^2+10c+25)-4c-20-7\
&=2c^2+16c+23
\end{align*}
Therefore, the answer is D.

If f(x)=2x2−4x−7f ( x ) = 2 x ^ { 2 } - 4 x - 7f(x)=2x2−4x−7

If $f ( x ) = 2 x ^ { 2 } - 4 x - 7$