## anonymous one year ago Find the standard form of the equation of the parabola with a vertex at the origin and a focus at (0, -7). @astrophysics

1. anonymous

this one is harder because it only gives u the focus

2. Astrophysics

|dw:1435909082458:dw| not really, it's sort of similar to your other one

3. Astrophysics

Can you figure out the directrix, remember how I said vertex is in the middle of directrix and focus, so your directrix will be?

4. anonymous

so it would be 7?

5. anonymous

@Astrophysics or (0,7)?

6. Astrophysics

Yes, good! |dw:1435909595769:dw| see how it's similar now to your previous question?

7. Astrophysics

So what way will the parabola go?

8. anonymous

you said it cant pass the directrix right?

9. Astrophysics

Yup!

10. anonymous

so it will go down?

11. anonymous

sorry im bad with determining which way the parabola goes

12. Astrophysics

|dw:1435910277561:dw| same as previous actually, remember it cannot pass the directrix

13. Astrophysics

$y = \frac{ 1 }{ 4p }(x-h)^2+k$ similar as previous question except now we have -7 as our p

14. anonymous

so i was right when i said down, haha im getting better atleast

15. Astrophysics

Yes you are :)

16. anonymous

y = -1/7x^2 y2 = -7x y =-1/28x^2 y2 = -28x

17. anonymous

y=-1/28x^2?

18. Astrophysics

Yeah, that sounds good

19. anonymous

thank you!

20. Astrophysics

Np, also notice the negative represents the vertical reflection, meaning the parabola will open down :), just a hint on the way to draw it if you get stuck :P