xy(x-y)-x(x-y)^2 =x(x-y)[y-(x-y)] =x(x-y)(y-x+y) =x(x-y)(2y-x) (a^2+b^2)^2-4a^2b^2 =(a^2+b^2-2ab) (a^2+b^2+2ab) =(a-b)^2(a+b)^23、(36分之一a-三分之一)a+1 =(a/36-1/3)a+1=a^2/36-a/3+1=1/36(a^2-12a+36)=1...