(1).(2x^2)^3-6x^3(x^3+2x^2+x)(2).(x+y+z)(x+y-z)(3).[(x+y)^2-(x-y)^2]÷(2xy)(4).a^2(a+1)^2-2(a^2-2a+4)

问题描述:

(1).(2x^2)^3-6x^3(x^3+2x^2+x)
(2).(x+y+z)(x+y-z)
(3).[(x+y)^2-(x-y)^2]÷(2xy)
(4).a^2(a+1)^2-2(a^2-2a+4)

(1).(2x^2)^3-6x^3(x^3+2x^2+x) =8x^6-6x^6-12x^5-6x^4=2x^6-12x^5-6x^4(2).(x+y+z)(x+y-z) =[(x+y)+z][(x+y)-z]=(x+y)^2-z^2=x^2+2xy+y^2-z^2(3).[(x+y)^2-(x-y)^2]÷(2xy) =(x+y+x-y)(x+y-x+y)÷(2xy)=2x*2y÷(2xy...