## anonymous one year ago Write the quadratic function in the form f(x)=a−(x-h)^ 2+k . Then, give the vertex of its graph.f(x)=-2x^2+8x-5

1. zzr0ck3r

$$f(x) = ax^2+bx+c$$ is the same thing as $$f(x) =a(x+\dfrac{b}{2a})^2+c-a(\dfrac{b}{2a})^2$$

2. anonymous

so i just plug it in?

3. sepeario

isn't the x point for the vertex -b/2a?

4. misty1212

hi!!

5. misty1212

this is not that hard it is $f(x)=-2x^2+8x-5$right?

6. anonymous

yes

7. misty1212

you want to write it as $f(x)=a(x-h)^2+k$ all you need is $$h$$ and $$k$$

8. misty1212

since evidently $$a=-2$$

9. misty1212

to find $$h$$ compute $$-\frac{b}{2a}$$ which, in your case, is $$-\frac{8}{2\times (-2)}$$

10. misty1212

what do you get ?

11. anonymous

is it -8/4x? and simplify so its -2x?

12. anonymous

or is it 2/x

13. anonymous

it's just 2 Kimes

14. anonymous

oh opps i mistaken x and a variable

15. anonymous

as*

16. zzr0ck3r

@Kimes yes just plug things :)