计算:
1
(x²-x³+x4)÷(- — x²)-(x+2)(x-2)
3
化简求值:
(x-2y) ²+(x+2y)(x-2y)-2(x-3y)(x-y),其中x=-4,y=0.5
计算:
1
(x²-x³+x4)÷(- — x²)-(x+2)(x-2)
3
化简求值:
(x-2y) ²+(x+2y)(x-2y)-2(x-3y)(x-y),其中x=-4,y=0.5
(1)-3+3X-3X^2-(X^2-4)=-3+3X-3X^2-X^2+4=-4X^2+3X+1
(2)X^2-4XY+4Y^2+X^2-4Y^2-2(X^2-XY-3XY+3Y^2)=2X^2-4XY-2X^2+8XY-6Y^2=4XY-6Y^2
代入得4×(-4)×0.5-6×0.5^2=-9.5