3y2-x2+(2x-y)-2(x2+3y2),其中x=1,y=-2先化简,再求值.

3y2-x2+(2x-y)-2(x2+3y2),其中x=1,y=-2先化简,再求值.
3y2-x2+(2x-y)-2(x2+3y2),其中x=1,y=-2
先化简,再求值.

3y2-x2+(2x-y)-2(x2+3y2),其中x=1,y=-2先化简,再求值.
3y2-x2+(2x-y)-2(x2+3y2)
=3y^2-x^2+2x-y-2x^2-6y^2
=-3x^2-3y^2+2x-y
=-3-12+2+2
=-11