计算(今晚急需!!!)

来源：百度知道 编辑：UC知道 时间：2024/06/07 08:43:38
1.a^2/a-b-b^2-2ab/b-a
2.1/a^2-4+1/a+2-1/2-a
3.a^2/a-1-a-1
4.1/6x-4y-1/6x-4y+3x/4y^2-9x^2
1.a-b分之a^2减去b-a分之b^2-2ab
2./a^2-4分之1加上a+2分之1减2-a分之1
3.a-1分之a^2减去a-1
4.6x-4y分之1减去6x+4y分之1加上4y^2-9x^2分之3x

1.a^2/(a-b)-(b^2-2ab)/(b-a)
=a^2/(a-b)+(b^2-2ab)/(a-b)
=(a^2+b^2-2ab)/(a-b)
=(a-b)^2/(a-b)
若a-b>0,则上式=a-b
若a-b<0,则上式=b-a
2.原式=1/(a^2-4)+1/(a+2)+1/(a-2)
=1/(a^2-4)+(a-2)/(a^2-4)+(a+2)/(a^2-4)
=(2a+1)/(a^2-4)
3.原式=a^2/(a-1)-(a-1)^2/(a-1)
=[a^2-(a-1)^2]/(a-1)
=(2ab-1)/(a-1)
4.原式=(6x+4y)/(36x^2-16y^2)-(6x-4y)/(36x^2-16y^2)-12x/(36x^2-16y^2)
=(2y-3x)/(9x^2-4y^2)