Сократите дробь x^2-18x+81/81-x^2

Question

Сократите дробь x^2-18x+81/81-x^2

Answer 1

x^2-18x+81=(x-9)^2

81-x^2=(9-x)(9+x)

(x-9)^2/(9-x)(9+x)=(x-9)(x-9)/(9-x)(9+x)=x-9/9+x