3道初二数学计算题

X^2+5X-6
--------- （约分）
X^2-3X+2

原式=(X-2)(X-3)/[(X-1)(X-2)]
=(X-3)/(X-1)

计算： A^2-1 2A-A^2
-------- + ---------
A^2-2A+A A^2-A-2

原式=[(A+1)(A-1)]/[A*(A-1)] + [A*(2-A)]/[(A+1)(A-2)]
=(A+1)/A + (-A/(A+1))
=(2A+1)/(A^2+A)

先化简，再求值：
X^2-Y^2 X
（---------)^2 除以 （X+Y) * (-----)^3 其中X=-1/2，Y=-1
XY X-Y

原式=[(X+Y)(X-Y)]^2/(X^2 * Y^2) * 1/(X+Y) * (X^3)/(X-Y)^3
=[X(X+Y)]/[Y^2 *(X-Y)]
∵X=-1/2，Y=-1
∴原式=3/2 =1.5

1.(x+6)(x-1)/(x-1)(x-2)=(x+6)(x-2)

2.(A+1)(A-1)/A(A-1)+A(2-A)/(A-2)(A+1)

=(A+1)/A-A/(A+1)

=(A+1)^2-A^2/A(A+1)

=(2A+1)/A(A+1)

3.(X+Y)^2(X-Y)^2/(XY)^2÷(X+Y)*X^3/(X-Y)^3

=X(X+Y)/Y^2(X-Y)

代入=3/2

X^2+5X-6 (x+6)(x-1) x+6
(1)--------- = -------------=----------
X^2-3X+2 (x-2)(x-1) x-2

(2)计算： A^2-1 2A-A^2 (A+1)(A-1) A(2-A)