1.[1/2x-y)^2+(1/2x+y)^2](1/2x^2-2y^2) 2.(2x^3-5x-4)(3x^2-7x+8) 简便运算

问题描述:

1.[1/2x-y)^2+(1/2x+y)^2](1/2x^2-2y^2) 2.(2x^3-5x-4)(3x^2-7x+8) 简便运算

[1/2x-y)^2+(1/2x+y)^2](1/2x^2-2y^2) 2
=(1/4x²-xy+y²+1/4x²+xy+y²)(1/2x²-2y²)
=(1/2x²+2y²)(1/2x²-2y²)
=1/4x^4-4y^4
(2x^3-5x-4)(3x^2-7x+8)
=6x^5-14x^4+16x³-15x³+35x²-40x-12x²+28x-32
=6x^5-14x^4+x³+23x²-12x-32

原式=(1/4x²-xy+y²+1/4x²+xy+y²)(1/2x²-2y²)=(1/2x²+2y²)(1/2x²-2y²)=1/4x^4-4y^4原式=6x^5-14x^4+16x³-15x³+35x²-40x-12x²+28x-32=6x^5-14...