ANSWER:
C. x = -7/3 and x = -3
STEP-BY-STEP EXPLANATION:
We have the following equation:
[tex]3x^2+16x+21=0[/tex]
We solve for x:
[tex]\begin{gathered} 16x=7x+9x \\ \\ \left(3x^2+7x\right)+\left(9x+21\right)=0 \\ \\ x\left(3x+7\right)+3\left(3x+7\right)=0 \\ \\ \left(3x+7\right)\left(x+3\right)=0 \\ \\ 3x+7=0\rightarrow3x=-7\rightarrow x=-\frac{7}{3} \\ \\ x+3=0\rightarrow x=-3 \end{gathered}[/tex]
Therefore, the correct answer is C. x = -7/3 and x = -3
