Question

先化简,再求值,a/(a+1)-(a+3)/(a-1)*(a^2-2a+1)/(a^2+4a+3),其中a是方程x^2+

Answer 1

化简：原式=a/(a+1)-(a+3)/（a-1）*（a-1)^2/[(a+2)^2-1]

=a/(a+1)-[（a-1)*(a+3)]/[(a+2-1)*(a+2+1)]

=a/(a+1)-(a-1)/(a+1)

=1/(a+1)

方程解得：a=-3±√13

带入即可得答案