x(2x-10)^2=72
x(x-5)^2-18=0
x^3-10x^2+25x-18=0
x^3-2x^2-8x^2+25x-18=0
x^2(x-2)-(8x-9)(x-2)=0
(x-2)(x^2-8x+9)=0
x=2,x=4+√7,x=4-√7