Question

化简求值(因式分解),过程

1.3(x-1)^3*y-(1-x)^3*z,其中x=1/2,y=1/5,z=-6/5
2.不解方程组
｛2x+y=6
｛x-3y=1 ,求7y(x-3y)^2- 2(3y-x)^2的值

Answer 1

解1.3(x-1)^3*y-(1-x)^3*z
=(x-1)^3*(3y+z)
=(1/2-1)^3*[3*1/5+(-6/5)]
=3/40
2.7y(x-3y)^2- 2(3y-x)^2
=7y-2
又因为 (2x+y)-2(x-3y)=7y=6-2=4
所以：原式=7y-2=4-2
=2