a) (x+3) - (2x/(x-2)) = (x-6)/(x-2)
=> (x+3)(x-2)/(x-2) - (2x/(x-2)) = (x-6)/(x-2)
=> (x+3)(x-2) - 2x = x-6
=> x^2+x-6 -2x = x-6
=> x^2-2x=0
=> x(x-2)=0
=> x = 0 hoặc x = 2
b) 3x/(x^2+2x+3) = (5x-3)/(x^2+2x+3)+1
=> 3x/(x^2+2x+3) = (5x-3)/(x^2+2x+3) +(x^2+2x+3)/(x^2+2x+3)
=> 3x = 5x-3+x^2+2x+3
=> x^2+4x = 0
=> x = 0 hoặc x = -4
c) (4-x)/(x^2-3x+2) = 2/(x^2-3x+2)+1
=> (4-x)/(x^2-3x+2) = 2/(x^2-3x+2)+ (x^2-3x+2)/(x^2-3x+2)
=> 4-x = 2+x^2-3x+2
=> x^2-2x = 0
=> x = 0 hoặc x = 2