Correct. Rewrite using a rational exponent: $\displaystyle{{\left({4}{{a}}^{{2}}{{b}}^{{40}}{{c}}^{{2}}\right)}}^{{\frac{{1}}{{4}}}}\usepackage{cmbright}\Huge\$

Use the laws of exponents to rewrite the expression: $\displaystyle{{4}}^{{\frac{{1}}{{4}}}}\cdot{{a}}^{{\frac{{2}}{{4}}}}\cdot{{b}}^{{\frac{{40}}{{4}}}}\cdot{{c}}^{{\frac{{2}}{{4}}}}\usepackage{cmbright}\Huge\$

Factor 4 and simplify the exponents: $\displaystyle{{\left({{2}}^{{2}}\right)}}^{{\frac{{1}}{{4}}}}\cdot{{a}}^{{\frac{{1}}{{2}}}}{{b}}^{{10}}{{c}}^{{\frac{{1}}{{2}}}}={{2}}^{{\frac{{1}}{{2}}}}{{a}}^{{\frac{{1}}{{2}}}}{{b}}^{{10}}{{c}}^{{\frac{{1}}{{2}}}}\usepackage{cmbright}\Huge\$

Change the factors with the exponent $\displaystyle\frac{{1}}{{2}}\usepackage{cmbright}\Huge\$ back to radical form: $\displaystyle{{b}}^{{10}}\sqrt{{{2}{a}{c}}}\usepackage{cmbright}\Huge\$

The missing radicand in the simplified expression is 2ac.