Correct. Rewrite using a rational exponent: $\displaystyle{{\left({9}{{m}}^{{20}}{{n}}^{{6}}{{p}}^{{2}}\right)}}^{{\frac{{1}}{{4}}}}\usepackage{cmbright}\Huge\$

Use the laws of exponents to rewrite the expression: $\displaystyle{{9}}^{{\frac{{1}}{{4}}}}\cdot{{m}}^{{\frac{{20}}{{4}}}}\cdot{{n}}^{{\frac{{6}}{{4}}}}\cdot{{p}}^{{\frac{{2}}{{4}}}}\usepackage{cmbright}\Huge\$

Factor 9 and simplify the exponents: $\displaystyle{{\left({{3}}^{{2}}\right)}}^{{\frac{{1}}{{4}}}}\cdot{{m}}^{{5}}{{n}}^{{\frac{{3}}{{2}}}}{{p}}^{{\frac{{1}}{{2}}}}={{3}}^{{\frac{{1}}{{2}}}}{{m}}^{{5}}{{n}}^{{\frac{{3}}{{2}}}}{{p}}^{{\frac{{1}}{{2}}}}\usepackage{cmbright}\Huge\$

Change the factors with rational exponents back to radical form: $\displaystyle{{m}}^{{5}}\sqrt{{{3}{{n}}^{{3}}{p}}}={{m}}^{{5}}{n}\sqrt{{{3}{n}{p}}}\usepackage{cmbright}\Huge\$

The missing radicand in the simplified expression is 3np.