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

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

先化简,再求值:2x+(2y²-x²)-(x²+2y²),其中x=1,y=-2.
原式=2x+2y²-x²-x²-2y²
=2x-2x²
=2-2
=0

2x+2y^2-x^2-x^2-2y^2
=2x-2x^2
=2x(1- x)
=0