[(x-2)分之3x -(x+2)分之x]乘 x分之(x²-4)
=[(x-2)分之3x ]乘 x分之(x²-4)- [(x+2)分之x]乘 x分之(x²-4)
=3(x+2) - (x-2)
=3x+6-x+2
=2x+8
=2(x+4)