Question

how do you multiply x-7 by x-7 when multiplying polynomials?

Answer 1

Let's multiply x - 7 * x - 7

$x^2-7x-7x+49=x^2-14x\text{ + 49}$

You multiply using the distributive property:

x * x, then x * -7, then x * - 7 and finally -7 * -7