已知x=-3,y=1/3,求-x^2-(3/2x^2-1/3y)+(2/3-2x^2)
问题描述:
已知x=-3,y=1/3,求-x^2-(3/2x^2-1/3y)+(2/3-2x^2)
答
原式=-x^2-3/2x^2+1/3y+2/3-2x^2
=-9/2x^2+1/3y+2/3
把x=-3,y=1/3带入
x^2=9
原式=-9/2*9+1/3*1/3+2/3
=-715/18