show that (px + qy)(pq + xy) = 4pxyq

Question

p, q, x, y are positive

Answer 1

Well, suppose:

    p=1

    q=2

    x=3

    y=4

 

Then, this says:

   (1*3 + 2*4)*(1*2 + 3*4) = 4*1*3*4*3

         11 * 14    =  144

            154  ≠  144

 

You will be working on this problem for a long time because they are not equal.