(12x³/(x-7))*((49-x²)/36x²)=(12x³/(x-7))*((7-x)(7+x)/36x²)= - (12x³/(7-x))*(7-x)(7+x)/36x²) = - (x(7+x))/3 = (7x+x²)/3
(12x³/(x-7))*((49-x²)/36x²)=(12x³/(x-7))*((7-x)(7+x)/36x²)= - (12x³/(7-x))*(7-x)(7+x)/36x²) = - (x(7+x))/3 = (7x+x²)/3