X的二次方减1分之X减4除以X的二次方加2X加1分之X的二次方减3X减4加x减1分之1

看你的题目都看了很少时间(x-4)/(x^2-1)÷(x^2-3x-4)/(x^2+2x+1)+1/(x-1)=(x-4)/(x^2-1)[(x^2+2x+1)/(x^2-3x-4)]+1/(x-1)=(x-4)(x+1)^2/[(x^2-1)(x-4)(x+1)]+1/(x-1)=(x+1)/(x^2-1)+1/(x-1)=(x+1)/[(x-1)(x+1)]+1/(x-1)=1/(x-1)+1/(x-1)=2/(x-1)