Answer
$2s^{2}+3st-5t^{2}$
Work Step by Step
We are given the expression $(s-t)(2s+5t)$. We can find the product of this expression using the FOIL method.
First terms: $s\times 2s=2s^{2}$
Outer terms: $s\times5t=5st$
Inner terms: $3-t\times 2s=-2st$
Last terms: $-t\times5t=-5t^{2}$
Adding together: $2s^{2}+5st+(-2st)+(-5t^{2})=2s^{2}+5st-2st-5t^{2}=2s^{2}+3st-5t^{2}$
