Сократите дробь a-x/a^2-x^2
A-x \ a^ 2-x^2 = (a-x) / (a+x) (a-x) = 1/ (a+x)
(a-x)/(a²-x²)=(a-x)/(a+x)(a-x) = 1/(a+x), x≠a,x≠-a