1
3x/(x-5)(x+5)+x/(x-5)=0
x≠5 x≠-5
3x+x²+5x=0
x²+8x=0
x(x+8)=0
x=0 x=-8
4
x≠2 x≠-1
(x+1)/(x-2)=a
17/4-a=1/a
17a-4a²-4=0
4a²-17a+4=0
D=289-64=225
a1=(17-15)/8=1/4
(x+1)(x-2)=1/4
4x+4=x-2
4x-x=-2-4
3x=-6
x=-2
a2=(17+15)/8=4
(x+1)/(x-2)=4
x+1=4x-8
4x-x=1+8
3x=9
x=3