Question

How do you factor the trinomial `s^2-4s-5`?

Answer 1

(s + 1)(s - 5)

Explanation:

y = s^2 - 4s - 5
Since a - b + c = 0, use shortcut. One factor is (s + 1) and the other is (s + c/a) = (s - 5).
Factored form: y = (s + 1)(s - 5)

Reminder of Shortcut.
When a + b + c = 0,
- One real root is 1 and the other is (c/a)
- One factor is (x - 1) and the other is (x - c/a)
When a - b + c = 0,
- One real root is (-1) and the other is (-c/a)
- One factor is (x + 1) and the other is (x + c/a)