system question

a = 48 / b^4

a^2  = 48^2 / b^8

     a^2  =  a^2

48^2 / b^8  = 24

b^8  = 48^2 / 24

b  = ± [ 48^2 / 24 ] ^(1/8)

b = ± [96]^(1/8)

Consider                                                                ab4  =  48  

We will divide both sides by ab.  

Since ab=72, we will divide the left side  

by "ab" and the right side by its equal 72.  

                                                                              ab4         48  

                                                                             ——   =   ——  

                                                                              ab           72  

Note that ab4 = (ab) * (b3)  

Cancel ab out of the left side.  

Reduce 48/72 on the right side.  

                                                                               b3           2  

                                                                             ——   =   ——  

                                                                                1            3  

                                                                                 b   =   cube root of (2 / 3)