「(a^2+2ab)^2」/(a+b)^2=「(a(a+2b))^2」/(a+b)^2=a^2(a+2b)^2/(a+b)^2(x^3-xy^2)/「-(x+y)」= x(x^2-y^2)/「-(x+y)」= x(x+y)(x-y)/「-(x+y)」=-x(x-y)(2x-5)^2=(-1+x）^2 (2x-5)^2-(x-1)^2=0(2x-5+x-1)(2x-5-x+1)...