## dinak23 2 years ago y=x^2-4x-12 factored is (x-6) (x+2), how do i determine vertex?

1. Compassionate

vertex form is y = a(x-h)^2 +k where vertex is (h,k)

2. dinak23

so how do i put this equation into vertex form?

3. dinak23

i just dont see where the h and k come in from

4. dinak23

(x^2-h)^2+k?

5. eSpeX

'h' and 'k' are just place holders. They, like 'a', can be anything.

6. dinak23

so how do i find the vertex now? what do i have to put in for h and k

7. Loser66

|dw:1372118543905:dw|

8. dinak23

You broke down 12 into a 4 and 8? I see that

9. dinak23

@loser66 why did you add 4 and subtract 4?

10. eSpeX

As @Loser66 pointed out, by adding (+4) and subtracting (-4) you are adding 0 to the equation.

11. dinak23

Is this completing the square?

12. eSpeX

Similar in principle but not the exact same thing. You are just massaging the equation to fit the form you need, without changing anything.

13. eSpeX

It's like multiplying two fractions to get a common denominator, or changing both sides of an equation equally, they are all about getting the numbers to "look" like what you need.

14. dinak23

I see what you guys did now

15. dinak23

Alright i understand, so the vertex is -2,-16 ?

16. dinak23

I just checked my answer sheet and thats right! Thanks alot!!

17. eSpeX

Yes, good job everyone. :D

18. dinak23

You guys are awesome!