## anonymous one year ago The equation f(x) = 3x2 − 24x + 8 represents a parabola. What is the vertex of the parabola? (−4, 152) (4, −40) (−3, 107) (3, −37)

1. anonymous

i dont know what a parabola is

2. anonymous

@DanJS

3. CGGURUMANJUNATH
4. anonymous

a symmetrical open plane curve formed by the intersection of a cone with a plane parallel to its side. The path of a projectile under the influence of gravity ideally follows a curve of this shape.

5. DanJS

you could complete the square to make the vertex equation form

6. anonymous

ok i know how to complete the sqaure

7. anonymous

8, 1\3

8. DanJS

y = a(x-h)^2 + k vertex at (h,k)

9. anonymous

huh?

10. anonymous

ive never heard of that

11. anonymous

this is so confusing

12. DanJS

the video that was linked is good

13. anonymous

ok ill watch it real quick brb

14. DanJS

If you havent done anything else yet , just plug in the numbers to that

15. anonymous

yea i dont get it

16. DanJS

$y = ax^2 + bx +c$ x coordinate of the vertex will be $\frac{ -b }{ 2a }$

17. DanJS

b = -24 a = 3

18. anonymous

so divide that?

19. DanJS

yes, just calculate it, put in the , a and b, values

20. anonymous

ok ill do that now

21. anonymous

i got -8b\a

22. DanJS

X - Coordinate of Vertex $\frac{ -b }{ 2a } = \frac{ -(-24) }{ 2*3 } = \frac{ 24 }{ 6 } = 4$

23. anonymous

i have to leave in like 3 minutes should i just guess??

24. anonymous

wait its b ???

25. DanJS

The X coordinate for the vertex is -b/(2a) = 4 To get the Y-Coordinate for that X value, plug in x=4 into the original y = 3x^2 - 24x + 8

26. DanJS

well you dont have to do that, if the X coordinate is 4, there is only one choice

27. anonymous

i just turned it in, b is right :)

28. DanJS

yea just have to remember the $\frac{ -b }{ 2a }$ for the x-coordinate of the vertex