Although this is a true equation, it is not the exponential form of the given equation. Remember that the base b is the number written below the line in the logarithmic equation. In this case, $\displaystyle{b}={7}\usepackage{cmbright}\Huge\$ . The correct answer is: $\displaystyle{{7}}^{{-{{3}}}}=\frac{{1}}{{343}}\usepackage{cmbright}\Huge\$