Question 777030
Take one term at a time.

Sqr(49) is what? 7, right? 

Sqr {{{x^2}}} is just x

and Sqr {{{y^4}}} is {{{y^2}}}

So we have {{{7xy^2}}}

If you don't follow, ask another question. Over time, you'll know this off the top of your head.