Multiply.
-$$\begin{array} { r }
6 x ^ { 2 } + 9 x + 5 \
\times \quad x + 7 \
\hline
\end{array}$$
A) $6 x ^ { 3 } + 51 x ^ { 2 } + 68 x + 35$
B) $48 x ^ { 3 } + 42 x ^ { 2 } + 63 x + 12$
C) $6 x ^ { 3 } + 42 x ^ { 2 } + 63 x + 35$
D) $48 x ^ { 3 } + 72 x ^ { 2 } + 40 x$

Question

Multiply.
-$$\begin{array} { r } 
6 x ^ { 2 } + 9 x + 5 \
\times \quad x + 7 \
\hline
\end{array}$$
A) $6 x ^ { 3 } + 51 x ^ { 2 } + 68 x + 35$
B) $48 x ^ { 3 } + 42 x ^ { 2 } + 63 x + 12$
C) $6 x ^ { 3 } + 42 x ^ { 2 } + 63 x + 35$
D) $48 x ^ { 3 } + 72 x ^ { 2 } + 40 x$

Quizplus · Accepted Answer

To multiply the given polynomials, distribute each term of the second polynomial across the first polynomial: $$(6x^2 + 9x + 5) \times (x + 7) = 6x^3 + 42x^2 + 63x + 35$$. However, there was a mistake in my calculation. Correctly, it should be: $$(6x^2 + 9x + 5) \times (x + 7) = 6x^3 + 9x^2 \times 7 + 6x^2 \times x + 9x^2 + 63x + 35 = 6x^3 + 42x^2 + 9x^2 + 63x + 35 = 6x^3 + 51x^2 + 63x + 35$$. Correcting the final step: $$6x^3 + 51x^2 + 63x + 35$$ is not an option, indicating a mistake in my recalculation. The correct process is: $$6x^3 + 42x^2 + 9x^2 + 63x + 5x + 35 = 6x^3 + 51x^2 + 68x + 35$$, which matches option A.

Multiply - 6x2+9x+5×x+7\begin{array} { r } 6 x ^ { 2 } + 9 x + 5 \\\times \quad x + 7 \\\hline\end{array}6x2+9x+5×x+7​​

Multiply
- $\begin{array} { r } 6 x ^ { 2 } + 9 x + 5 \\\times \quad x + 7 \\\hline\end{array}$