Answer
$15x^{5}+42x^{3}-8x^{2}$
Work Step by Step
$4x^{2}(5x^{3}+3x-2)=(4x^{2})(5x^{3}) +(4x^{2})(3x)+(4x^{2})(-2)$
$=20x^{5}+12x^{3}-8x^{2}\qquad (*)$
$-5x^{3}(x^{2}-6)=-5x^{3}(x^{2})-5x^{3}(-6)$
$=-5x^{5}+30x^{3}\qquad(**)$
Combine like terms of (*) and (**)
Problem=$(20x^{5}-5x^{5})+(12x^{3}+30x^{3})-8x^{2}$
=$15x^{5}+42x^{3}-8x^{2}$
