Question

Fourth root of 128x^7 y^7

Answer 1

Fourth root of 128x^7 y^7  = ⁴√(128x⁷y⁷)

We would then expand (128x⁷y⁷)

                                     = ⁴√(2*2*2*2*2*2*2*x*x*x*x*x*x*x*y*y*y*y*y*y*y)

For every four 2's we bring out one 2 out of the radical, and for every four x's and four y's we bring out one x and one y out of the radical.
              
                                    = (2*x*y)   ⁴√(2*2*2*x*x*x*y*y*y)

                                    = (2*x*y)    ⁴√(8x³y³)
                                              
                                   = 2xy  ⁴√(8x³y³)
                               
Note the 4 is associated with the radical sign which covers 8x³y³

Answer 2

128^1/4 x^7/4 y^7/4


i need 20 letters, stil  not enough