Who is asking: Student
example : v/"" v/"" 81y8
You can take the squarre roots in succession. In your example the Sqrt(81) is 9 and Sqrt(y8) is y4 so Sqrt(81 y8) is 9 y4.
Now apply the second square root operation. Sqrt(9) = 3 and Sqrt(y4) = y2. Thus Sqrt(9 y4) = 3 y2.