a+b b-c
(1) —— - ——
ab bc
c(a+b) a(b-c)
= ———— - ———
abc abc
ac+bc-ab+ac
= ——————
abc
2ac+bc-ab
= —————
abc
x-3 2
(2) ——— - ———
x²-1 1+x
x-3 2
= ————— - ———
(x+1)(x-1) x+1
x-3 2(x-1)
= ————— - —————
(x+1)(x-1) (x+1)(x-1)
x-3-2x+2
= —————
(x+1)(x-1)
-x-1
= —————
(x+1)(x-1)
-1
= ——
x+1