Выражение 1 a^2 (a+1+ / a-1 1-2a+a^2

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

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