Answer
$7x^{3}+14x^{2}-7x$
Work Step by Step
$7x(x^{2}+2x-1)=(7x)(x^{2})+(7x)(2x)+(7x)(-1)=7x^{3}+14x^{2}+(-7x)=7x^{3}+14x^{2}-7x$
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