解下列方程..1.(x/x-5)=(x-2)/(x-3)2.(6x-1)/(3x+2)=(4x-7)/(2x-5)3.{

1.(x/x-5)=(x-2)/(x-3)
x(x-3)=(x-2)(x-5)
x^2-3x=x^2-7x+10
4x=10
x=5/2
2.(6x-1)/(3x+2)=(4x-7)/(2x-5)
(6x-1)(2x-5)=(4x-7)(3x+2)
12x^2-32x+5=12x^2-13x-14
19x=19
x=1
3.{1/(x^2+5x+6)}={1/(x+2)}+{1/(x+3)}
{1/(x+2)(x+3)}={1/(x+2)}+{1/(x+3)}
1=(x+3)+(x+2)
2x+5=1
2x=-4
x=-2
但:x≠-2,-3
方程无解
4.解关于x的方程{(a+b)/x}+(a/b)=-1(a+b≠0)
{(a+b)/x}=-1-a/b
{(a+b)/x}=-(a+b)/b
1/x=-1/b
x=-b
5.解方程{[1/(x-5)]+[1/(x-9)]}={[1/(x-8)]+[1/(x-6)]}
{[1/(x-9)]-[1/(x-8)]}={[1/(x-6)]-[1/(x-5)]}
[(x-8)-(x-9)]/(x-8)(x-9)=[(x-5)-(x-6)]/(x-5)(x-6)
1/(x-8)(x-9)=1/(x-5)(x-6)
(x-8)(x-9)=(x-5)(x-6)
x^2-17x+72=x^2-11x+30
6x=42
x=7