Verified Answer :

\(\sqrt[7]{x} * \sqrt[7]{x} * \sqrt[7]{x}= \sqrt[7]{ x^{3} }\)
Thank you.

It is not actually a tough problem but the way the problem has been presented creates confusion in the mind. The answer to this problem is sqrt[7]{ x^{3} }. Now if we have to simplify this problem for you, then it would look something like the expression i am giving below. 
sqrt[7]{x} sqrt[7]{x} sqrt[7]{x}
I hope the answer has come to your help.