Question

помогите с 3!!!!!!!!!!

Answer 1

(n-7)(n+7)/(n-7)^2:(n^2+7a)/3*(n-7)=(n+7)*3*(n-7)/(n-7)(n^2+7a)=(3(n+7)/(n^2+7a)=3*(90+7)/(90^2+7a)=291/(8100+7a)