1）=（2a+b)/[(2a+b)(2a-b)]-(2a-b)/[(2a+b)(2a-b)]
=[(2a+b)-(2a-b)]/[(2a+b)(2a-b)]
=2b/[(2a+b)(2a-b)]
=2b/(4a²-b²)
2)=x=2(x+3)／2(x+3)(x－3﹚－12／2(x+3)(x-3)－﹙x－1)(x-3)／2(x+3)(x-3)/（x-1)-（x-1)
=x²/(x-1)-(x-1)²/(x-1)
=[x²-(x-1)²]/(x-1)
=(2x-1)/(x-1)
3)=1／(x－3﹚－6／(x+3)(x-3)－﹙x－1)／2(x+3)
=2(x+3)／2(x+3)(x－3﹚－12／2(x+3)(x-3)－﹙x－1)(x-3)／2(x+3)(x-3)
=[2(x+3)－12－﹙x－1)(x-3)]／2(x+3)(x-3)
=(-x²+6x-9)/2(x+3)（x-3)
=-(x-3)²/2（x+3)（x-3)
=-(x-3)/2(x+3)
=(3-x)/(2x+6）