Question

Find the zeros of the function x^2 - x-4

Answer 1

Do you know how to factor this equation?

Answer 2

Yes but my problem is, is that I can't think of anything that added toger is 1 and multi to get 4

Answer 3

Hm. Fair enough. So there are a couple of ways to approach this. Do you know the quadratic formula?

Answer 4

yes -2 +- \[-b +_\sqrt{b^2 - 4ac} \over 2a\]

Answer 5

Right. Do you know what a, b, and c are in your equation?

Answer 6

yes a is 1x^2 b is 1x and c is 4

Answer 7

Close, a, b, and c are the coefficients -- so a is 1, b is -1, and c is -4. Remember that a minus sign is part of the coefficient :)

Can you plug those in?

Answer 8

yeah I get \[1 \pm \sqrt{15} \over 2\]

Answer 9

Right-o. And there are your two zeros.

Answer 10

what are the two zeros?

Answer 11

The quadratic equation describes two results:

\[x = \frac{1 + \sqrt{15}}{2}\]
and
\[x = \frac{1 - \sqrt{15}}{2}\]

Those are the two zeros of the equation.

Answer 12

oh, ok thanks alot

Answer 13

No problem, glad to help :)

Answer 14

wouldn't this be 17 instead of 15?