Question

已知a平方+2a-1=0,求分式的值

Answer 1

1/(a+1)-(a+3)/(a^2-1)*(a^2-2a+1)/(a^2+4a+3)

=1/(a+1)-(a+3)/(a+1)(a-1)*(a-1)^2/(a+3)(a+1)

=1/(a+1)-(a-1)/(a+1)^2

=(a+1)/(a+1)^2-(a-1)/(a+1)^2

=2/(a^2+2a+1)

=2/2=1