1.计算:-(-a²b+4ab-2)+2(a²-3ab-3)过程留着留在上面!2.先化简,再求值先化简,再求值:1.(a-2)²-(2a-1)(2a+1)其中a=-22.x(x+2y)-(x+1)²+2x,其中x=25分之一,y=-25

问题描述:

1.计算:-(-a²b+4ab-2)+2(a²-3ab-3)过程留着留在上面!2.先化简,再求值
先化简,再求值:
1.(a-2)²-(2a-1)(2a+1)其中a=-2
2.x(x+2y)-(x+1)²+2x,其中x=25分之一,y=-25

1.计算:-(-a²b+4ab-2)+2(a²-3ab-3)
=a²b-4ab+2+2a²-6ab-6
=a²b-10ab+2a²-4
1.(a-2)²-(2a-1)(2a+1)其中a=-2
=a²-4a+4-(4a²-1)
=a²-4a+4-4a²+1
=-3a²-4a+5
=-3*4+4*2+5
=1
2.x(x+2y)-(x+1)²+2x,其中x=25分之一,y=-25
=x²+2xy-(x²+2x+1)+2x
=2xy-1
=2*1/25*(-25)-1
=-2-1
=-3