what is another expression that I can use for this problem ?[tex] \sqrt[c]{a ^{b} } [/tex]

The expression:
[tex]7^{\frac{9}{4}}\text{ can be re}written\text{ once the laws of indices have b}een\text{ applied}[/tex]Applying the fractional laws of indices, where the denominator becomes a root and the numerator an index.
[tex]7^{\frac{9}{4}}=\sqrt[4]{7^9}[/tex]Comparing the expression with,
[tex]\begin{gathered} \sqrt[c]{a^b}\text{ } \\ \therefore\text{ }\sqrt[4]{7^9}\text{ =}\sqrt[c]{a^b} \end{gathered}[/tex]Hence, a = 7, b = 9, c = 4