Question

计算(a^2-1)分之(4a)+(1-a)分之(1+a)

Answer 1

(a^2-1)分之(4a)+(1-a)分之(1+a)

=(4a)/(a+1)(a-1)-(a+1)(a+1)/(a-1)(a+1)

=[4a-(a+1)^2]/(a+1)(a-1)

=(4a-a^2-2a-1)/(a+1)(a-1)

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

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

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