Question

Rút gọn biểu thức a) (2x-y)^3-6.(2x-y).x+12(2x-y).x^2-8x^3 b) x^2.(x+3)(x-3)-(x^2-1)(x^2+1) c) (x-y)^2-2(x-y)(x+y)+(y+x)^2

Answer 1

a, sửa đề\(\left(2x-y\right)^3-6\left(2x-y\right)^2x+12\left(2x-y\right)x^2-8x^3=\left(2x-y-2x\right)^3=\left(-y\right)^3=-y^3\)

b, \(x^2\left(x+3\right)\left(x-3\right)-\left(x^2-1\right)\left(x^2+1\right)=x^2\left(x^2-9\right)-\left(x^4-1\right)=x^4-9x^2-x^4+1=\left(1-3x\right)\left(3x+1\right)\)

c, \(=\left(x-y-x-y\right)^2=\left(-2y\right)^2=4y^2\)