Question

What are the zeroes of y = x2 – 2x – 15?
–3, –5
3, 5
–3, 5
3, –5

Answer 1

y = x^2 – 2x – 15

we need to factor this equation or use the quadratic equation.
can you do either one of these?

Answer 2

(x - 3) (x + 5)
(-3, 5)?

Answer 3

No, because you need to make the whole side of the equation equal to zero.
What would make (x - 3) zero?

Answer 4

and also, you factored wrong. that would be correct if it was y = x2 + 2x – 15, but it's a negative 2x, your close, try again.

Answer 5

"(x - 3) (x + 5) "
"(-3, 5)?"

close!!
but if we FOILed this out what do we get?
(x - 3) (x + 5)
x^2 +5x -3x -15
x^2 +2x -15

the sign on the 2x is positive, and we need a negative, so if we did
(x + 3) (x - 5)
x^2 -5x +3x -15
x^2 -2x -15

so, the zeros are
0 = (x+3)
0 = (x-5)
x = -3 and 5

so, you have the right idea, just got a little mixed up. ^_^

Answer 6

*sorry, open study isn't working at all today for me!!