Work Step by Step
By multiplying each term of the polynomial by the monomial, and then adding the products, we have $$5x^4(2x^3+8x^2-1)=5x^4(2x^3)+5x^4(8x^2)-5x^4(1)\\ =10x^7+40x^6-5x^4.$$
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.