Question 371280
{{{(x-4)(x^2+3x+5)}}}
When multiplying polynomials you multiply each term of one polynomial by each term of the other. Then you add like terms, if any. I find it helps avoid errors if subtractions are rewritten as additions of the opposite:
{{{(x + (-4))(x^2+3x+5)}}}
{{{x*x^2 + x*3x + x*5 + (-4)*x^2 + (-4)*3x + (-4)*5}}}
Multiplying out we get:
{{{x^3 + 3x^2 + 5x + (-4*x^2) + (-12x) + (-20)}}}
Adding like terms:
{{{x^3 + (-1*x^2) + (-7x) + (-20)}}}
or
{{{x^3 -x^2 -7x -20}}}