计算 x-1/x²-4 - 2/2+x
问题描述：
计算 x-1/x²-4 - 2/2+x
答
原式=(x-1)/[(x+2)(x-2)]-2(x-2)/[(x+2)(x-2)]
=[x-1-2(x-2)] /[(x+2)(x-2)]
=[x-1-2x+4]/[(x+2)(x-2)]
=(3-x)/(x²-4)