(a²-1)/(a²-a-2)÷a/(2a-4)
=2(a+1)(a-1)(a-2)/a(a+1)(a-2)
=2(a-1)/a
=2(1/2-1)/(1/2)
=4*(-1/2)
=-2
如果不懂,祝学习愉快!第二部和第三部的过程能再详细点吗a²-a-2=(a+1)(a-2)
其余的就是消元，把相同的消去