a, : x+2/x-2 - 1/x = 2/x(x - 2)
⇔ x(x+2)/x(x-2) - x-2/x(x-2) = 2/x(x-2)
⇒ x²+2x - x+2 = 2
⇔ x²+x = 0
⇔ x(x+1)=0
⇔ x+1=0 ⇔ x=-1
b, : 5 - (x-6) = 4 (3-2x)
⇔ 5-x+6=12-8x
⇔ 11-x = 12-8x
⇔ -1 = -7x
⇔ x = 1/7
c, : 2x (x-3) + 5 ( x -3 ) = 0
⇔ (x-3)(2x+5)=0
⇔ x-3=0 ⇔ x=3
2x+5=0 ⇔ x=-5/2