(b-2a)^2÷(-b/a)*(-3b/4a)^3(x-1/x+2)*(x^2-4/x^2-2x+1)÷1/x^2-1
(b-2a)^2÷(-b/a)*(-3b/4a)^3
(x-1/x+2)*(x^2-4/x^2-2x+1)÷1/x^2-1