\(d,\dfrac{343}{125}=\left(\dfrac{7}{5}\right)^x\)
\(\left(\dfrac{7}{5}\right)^3=\left(\dfrac{7}{5}\right)^x\)
\(\Rightarrow x=3\)
\(e,\dfrac{x+3}{12}=\dfrac{3}{x+3}\)
\(\left(x+3\right).\left(x+3\right)=12.3\)
\(\left(x+3\right).\left(x+3\right)=36\)
\(\left(x+3\right)^2=36\)
\(\left(x+3\right)^2=\left(\pm6\right)^2\)
\(\left[{}\begin{matrix}x+3=6\\x+3=-6\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=6-3\\x=-6-3\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=3\\x=-9\end{matrix}\right.\)
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