Find $( x + 9 ) ^ { 3 }$ . Don t forget that $( x + 9 ) ^ { 3 }$ means ( x + 9)( x + 9)( x + 9).
A) $x ^ { 3 } + 27 x ^ { 2 } + 81 x + 729$
B) $x ^ { 3 } + 27 x ^ { 2 } + 243 x + 729$
C) $x ^ { 3 } + 9 x ^ { 2 } + 81 x + 729$
D) $x ^ { 3 } + 27 x ^ { 2 } + 243 x + 81$
E) $x ^ { 3 } + 9 x ^ { 2 } + 81 x + 81$

Question

Quizplus · Accepted Answer

To expand $(x+9)^3$, we can use the binomial expansion formula or simply multiply out the expression:

\begin{align*}
(x+9)^3 &= (x+9)(x+9)(x+9) \
&= (x^2+18x+81)(x+9) \
&= x^3 + 9x^2 + 81x + 18x^2 + 162x + 729 \
&= x^3 + 27x^2 + 243x + 729 \
\end{align*}

Therefore, the answer is B.

Find (x+9)3( x + 9 ) ^ { 3 }(x+9)3 Don T Forget That

Find $( x + 9 ) ^ { 3 }$ Don T Forget That