## soccerrocks34555 3 years ago Suppose a parabola has a vertex (-8,-7) and also passes through the point (-7,-4). write the equation of the parabola in vertex form.

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1. klimenkov

\(y+7=3(x+8)^2\)

2. soccerrocks34555

The answer is y=3(x+8) -7 .. I just dont know how to get it

3. Brittni0605

Vertex form is: \[a(x-h)^{2}+k\]

4. Brittni0605

5. soccerrocks34555

I know that but when I plug the problem into it I don't get the correct answer. What am I doing wrong. Can you please explain how to do it to me

6. soccerrocks34555

So -8 and -7 are vertex

7. Brittni0605

-8 = h -7= k

8. soccerrocks34555

a ( -7+8) Squared + 7 is that right

9. klimenkov

Subtract -7 from both sides of my equation.

10. Brittni0605

No.

11. Brittni0605

|dw:1352657063399:dw|

12. soccerrocks34555

Okay. So now do we have to plug in the other points that it passes through

13. Brittni0605

|dw:1352657115052:dw|

14. soccerrocks34555

Then do I add 4 to the 7 ?

15. Brittni0605

No, because you want to solve for a. SO add the 7 to the 4

16. soccerrocks34555

which is 3

17. Brittni0605

Yes.

18. Brittni0605

|dw:1352657369387:dw|

19. soccerrocks34555

ahhh I get it now! Thank you so much for your help. Changing topics can you help me with another problem?

20. Brittni0605

Sure.

21. soccerrocks34555

What point in the feasible region minimizes the objective function? X > 0 y>0 y<4 Y < -x +5 Above are the constraints Objective Function: C= -9x+y The answer is (5,0) but I don't understand how to get it.

22. Brittni0605

23. soccerrocks34555

okay no problem!

24. Brittni0605

|dw:1352658011264:dw|

25. soccerrocks34555

okay.

26. soccerrocks34555

I was thinking you had to plug some stuff in to get the final answer

27. Brittni0605

I used my graphing calc. I graphed y=-x+5

28. Brittni0605

the x intercept of that is (5,0)

29. soccerrocks34555

That's the vertex.. right

30. soccerrocks34555

Cause have another example of a problem like that.. & that doesn't work Graph the system of constraints and find the value of x and y that minimize the objective function. 20. Constraints x ≥ 0 y ≥ 0 y ≤ 3 y < − 2x + 5 Ï Ì Ó Objective function: C = −8x + 5y

31. Brittni0605

(5,0) is the vertex because y=-x+5 is a line

32. soccerrocks34555

33. soccerrocks34555

ohh i see what your saying

34. Brittni0605

If you graph, y=-2x+5, your x intercept is (5/2, 0)

35. soccerrocks34555

how do you see that..

36. soccerrocks34555

I put it in my graphing calculator