Question

Please factorise p^2-16p-80

Answer 1

(p - 20)(p + 4).

Explanation:

p^2 - 16p - 80

We need 2 numbers whose product is -80 and whose sum is -16. They are -20 and + 4.

So we have the result p^2 - 16p = 80 = (p - 20)(p + 4).

Answer 2

p^2 - 16p - 80

Vieta's formulas

because 4 * (-20) = -80 and 4 + (-20) = -16

p^2 - 16p - 80 = (p + 4)(p - 20)