(x – 3)(x2 – 4x – 7) simplify

Question

this is a question that i dont understand. assistance please?

Answer 1

(x-3)(x^(2)-4x-7)

Multiply each term in the first polynomial by each term in the second polynomial.
(x*x^(2)+x*-4x+x*-7-3*x^(2)-3*-4x-3*-7)

Multiply each term in the first polynomial by each term in the second polynomial.
(x^(3)-7x^(2)+5x+21)

Remove the parentheses around the expression x^(3)-7x^(2)+5x+21.
x^(3)-7x^(2)+5x+21