化简求值；{[(a-2)/(a^2+2a)]-[(a-1)/(a^2+4a+4)]}除以(a-4)/(a+2),其中a满足a^2+2a-1=0
问题描述：
化简求值；{[(a-2)/(a^2+2a)]-[(a-1)/(a^2+4a+4)]}除以(a-4)/(a+2),其中a满足a^2+2a-1=0
应该能看懂吧
答
{[(a-2)/(a^2+2a)]-[(a-1)/(a^2+4a+4)]}除以(a-4)/(a+2)={[(a-2)/a(a+2)]-[(a-1)/(a+2)²]}除以(a-4)/(a+2)=[(a+2)(a-2)-a(a-1)]/a(a+2)²×(a+2)/(a-4)=1/(a²+2a)=1a的值是多少，关键是求值a^2+2a-1=0a^2+2a=1{[(a-2)/(a^2+2a)]-[(a-1)/(a^2+4a+4)]}除以(a-4)/(a+2)={[(a-2)/a(a+2)]-[(a-1)/(a+2)²]}除以(a-4)/(a+2)=[(a+2)(a-2)-a(a-1)]/a(a+2)²×(a+2)/(a-4)=1/(a²+2a)=1/1=1不用求出a的值,求出a²+2a=1,化简后代入就可以了