## Calculus with Applications (10th Edition)

$6x(x^{3}+7)(-2x^{3}-5x+7)$
$6x(x^{3}+7)^{2}-6x^{2}(3x^{2}+5)(x^{3}+7)$ greatest common factor=$6x(x^{3}+7)$ $=[6x(x^{3}+7)]\cdot(x^{3}+7)-[6x(x^{3}+7)]\cdot x(3x^{2}+5)$ $=6x(x^{3}+7)[(x^{3}+7)-x(3x^{2}+5)]$ $...$ simplify the expression in brackets $=6x(x^{3}+7)(x^{3}+7-3x^{3}-5x)$ $=6x(x^{3}+7)(-2x^{3}-5x+7)$