Question

What are the zeroes of y = x^2 – 2x – 15?
–3, –5
3, 5
–3, 5
3, –5

I believe it's D (3, -5)

Answer 1

y = x^2 – 2x – 15
x^2 – 2x – 15 = 0
(x - 5) (x + 3)

Answer 2

Common mistake, what is the number that will make x - 5 or x + 3 zero?

Answer 3

Hint, -5 -5 = -10 it's not the right answer.

Answer 4

-3, 5?

Answer 5

Yeah, exactly.

Answer 6

But how does that fit in with factoring?

Answer 7

Look
\[0 = (5-5) (5 + 3) = 0 \times 8 = 0 \]
\[0 = (-3-5)(-3 + 3) = -8 \times 0 = 0\]

Answer 8

I see my mistake \facepalm thanks!