c)<=>1/x-2 +3.(x-2)/x-2=3-x/x-2
<=>1/x-2+3x-6/x-2=3-x/x-2
=>1+3x-6=3-x
<=>1+3x-6-3+x=0
<=>3x+x=-1+6+3
<=>4x=8
<=>x=2
Vậy tập nghiệm phương trình S={2}
i)90/x-36/x-2=2
<=>90.(x-2)/x(x-2)-36.2/(x-2).2=2.2.(x-2)/2.(x-2)
=>90x-180-72=4x-4
<=>90x-4x=180+72-4
<=>86x=248
<=>62/17