(1) 3/(X-2) (X-1) - 1/X-2 (2) x/2-x - 4-x²/x²-4x+4
=3/(X-2) (X-1) - X-1/ (X-2) (X-1) =X/2-X - (2+X)(2-X)/(X-2)(X-2)
=3-X+1/(X-2) (X-1) =X/2-X - 2+X/2-X
=4-X/(X-2) (X-1) =X-2-X/2-X
(3) 2/a²-1 + 1/a+1 =2/X-2
=2/(a+1)(a-1) + 1/a+1
=2/(a+1)(a-1) + a-1/(a+1)(a-1)
=2+a-1/(a+1)(a-1)
=3+a/a²-1