ANSWER:
B. 0.45
STEP-BY-STEP EXPLANATION:
We have the following equation:
[tex]6\cdot2^{4x}^{}=21[/tex]We solve for x:
[tex]\begin{gathered} 2^{4x}=\frac{21}{6} \\ \ln \: \mleft(2^{4x}\mright)=\ln \: \mleft(\frac{7}{2}\mright) \\ 4x\cdot\ln (2)=\ln \: \mleft(\frac{7}{2}\mright) \\ x=\frac{\ln \: \mleft(\frac{7}{2}\mright)}{4\cdot\ln (2)} \\ x=0.45 \end{gathered}[/tex]The value of x is 0.45