Question

Reviewing my algebra please check.
What are the zeros of \(y = x^2 - 2x -15\)?
(-3, 5) is what I got.

Answer 1

0=(x-5)(x+3)
x=5,3

Answer 2

Set the equation to equal to zero: $$x^2 - 2x -15 = 0$$

$$(x - 5)(x + 3)$$

Use FOIL:
$$x^2 + 3x - 5x - 15$$
$$x^2 - 2x - 15$$
$$(5 - 5) = 0 = (-3 + 3)$$
\(\textbf{Hence the zeros are:}\)
(-3, 5)

So you are correct.

Answer 3

Well, hold on guys. Don't out them in (-3, 5) format

Answer 4

Are there any other methods I could use other than this?

Answer 5

That's a coordinate, tecchnically, and would be marked wrong by a teacherif placed as the answer

Answer 6

that isn't meant to be a non-inclusive range but rather the 2 discrete values

Answer 7

I believe graphing is another method. Not 100% sure.

Answer 8

You could do that.

Answer 9

@LanguageEnthusiast want me to show you?

Answer 10

@Algorithmic sure if you don't mind :3 I would hate to be a bother.

Answer 11

Imagine a graph as such:


See where I circled the graph, the place where the parabola intersects the x-axis are where the zeros would be.

Answer 12

Oh I see! I remember this actually thank you so much! :-)

Answer 13

You are welcome, also it is never a bother in my opinion to ask for knowledge. So ask away. :-)