Answer
$-3x^{2}-x-2$
Work Step by Step
If
(Polynomial 1) - (Polynomial 2)=(Difference),
then
(Polynomial 1) - (Difference)=(Polynomial 2).
$(5x^{2}-2x+1)-(8x^{2}-x+3)=\qquad$. distribute the minus, lose parentheses
$=5x^{2}-2x+1-8x^{2}+x-3\qquad$ ... gather like terms
$=(5x^{2}-8x^{2})+(-2x+x)+(1-3)$
$= -3x^{2}-x-2\qquad $=(Polynomial 2)