先化简,再求值：x2y-[4x2y-(xyz-x2z)-3x2z]-2xyx,其中x的倒数等于其本身,|y|=3,x2=4,且x>_数学解答

先化简,再求值：x2y-[4x2y-(xyz-x2z)-3x2z]-2xyx,其中x的倒数等于其本身,|y|=3,x2=4,且x>z>y,xyz

人气：277 ℃　时间：2020-05-24 15:35:06

解答

x=±1,y=±3,z=±2
xyzz>y
则0>x>z>y
x=-1,y=-3,z=-2,
x2y-[4x2y-(xyz-x2z)-3x2z]-2xyx
=x2y-4x2y+xyz-x2z+3x2z-2xyx
=-3x2y-xyz-2x2z
=9+6+4
=19