Question 154071
(6x+3)(3x+7) = 6x(3x+7)+3(3x+7) = 18x^2+42x+9x+21 = 18x^2+51x+21


(7x-1)(18x^2+51x+21) = 126x^3+357x^2+147x-18x^2-51x-21 = 126x^3+339x^2+96x-21