先化简,再求值;3(x²+1/3y)-2(3/2x²-xy)+(-y+3x),其中x=-2,y=1/2

先化简,再求值;3(x²+1/3y)-2(3/2x²-xy)+(-y+3x),其中x=-2,y=1/2
先化简,再求值;3(x²+1/3y)-2(3/2x²-xy)+(-y+3x),其中x=-2,y=1/2

先化简,再求值;3(x²+1/3y)-2(3/2x²-xy)+(-y+3x),其中x=-2,y=1/2
3(x²+1/3y)-2(3/2x²-xy)+(-y+3x),
=3x²+y-3x²+2xy-y+3x
=2xy+3x
当x=-2,y=1/2时
原式=2×(-2)×1/2+3×(-2)=-2-6=-8