Ans: B
By using the intercept form, we have
By using the intercept form, we have
$\begin{array}{rcl}
\dfrac{\log_3 x}{8} + \dfrac{\log_9 y}{7} & = & 1 \\
7 \log_3 x + 8\log_9 y & = & 56 \\
7 \log_3 x + \dfrac{8\log_3 y}{\log_3 9} & = & 56 \\
7 \log_3 x + \dfrac{8\log_3 y}{2} & = & 56 \\
7 \log_3 x + 4\log_3 y & = & 56 \\
log_3x^7 + \log_3y^4 & = & 56 \\
\log_3(x^7y^4) & = & 56 \\
x^7y^4 & = & 3^{56}
\end{array}$
