## shaleiah one year ago @Nnesha

1. shaleiah

2. Nnesha

3. Nnesha

|dw:1443039690740:dw|

4. Nnesha

for the first part we need to find max in other words vertex point |dw:1443039751009:dw|

5. Nnesha

so use the formula to find c-coordinate of the vertex $\huge\rm x=\frac{ -b }{ 2a }$ b=middle term a=leading coefficient

6. Nnesha

hmm 407 ??

7. shaleiah

Wait...

8. shaleiah

$\frac{ 0.658 }{ 2(0.00407) }$

9. Nnesha

don't forget the sign okay $\frac{ -0.658 }{ 2(-0.00407) }$ now solve

10. shaleiah

80.83538084

11. Nnesha

something wrong i didn't get that o.O

12. shaleiah

I typed it in my ti-84 calculator, that's what I got..

13. Nnesha

try again put the parentheses

14. Nnesha

that's how you should type in ti 84 -(.658)/(2(-.000407))

15. shaleiah

$-(\frac{ .658 }{ 2(-.000407) }= 808.3538084$

16. Nnesha

yes right now that's x coordinate of vertex now substitute x for 808 to find y-coordinate into the original equation

17. IrishBoy123

|dw:1443040813328:dw|

18. Nnesha

what ?? o.O

19. Nnesha

hmm i mean $y=-.000407x^2+.658x$ in this equation replace x with 808

20. shaleiah

265.948352

21. Nnesha

yes right we can round it so it would be 266 that would be the height

22. Nnesha

now for the 2nd part you need to find x-intercept(zeros ) of that quadratic equation

23. Nnesha

i'll like to use quadratic formula bec there are negative numbers

24. shaleiah

I'm not good at quadratic formulas:(

25. Nnesha

$\huge\rm \frac{ -b \pm \sqrt{b^2-4ac} }{ 2a }$ quadratic formula a= leading coefficient b=middle term c=constant so justplugin

26. Nnesha

$\huge\rm Ax^2+Bx+C$ quadratic equation a= leading coefficient b=middle term c=constant

27. shaleiah

$\frac{ -.658 +\sqrt{.658^{2}-4(.00407)}}{ 2(266) }$

28. Nnesha

don't forget the C which is 0 so 4ac would be 4(.000407)(0) and why did you replace a with 266 ?

29. Nnesha

the denominator is 2a so 2(????)

30. shaleiah

2(.000407)

31. Nnesha

yes right $\frac{ -.658 +\sqrt{(.658)^{2}-4(.00407)(0)}}{ 2(.000407) }$ now oslve

32. Nnesha

solve**

33. shaleiah

807545.4545

34. Nnesha

please show you u got that that's not right you should get 2 solutions

35. shaleiah

I typed the equation directly in my ti-84 calculator

36. shaleiah

Do i solve them seperately?

37. Nnesha

hmm that wouldn't work how would you right plus minus sign in the calculator yes right solve the numerator the square root part

38. shaleiah

1.316

39. shaleiah

or .658?

40. Nnesha

both are wrong first solve square root $\frac{ -.658 +\sqrt{\color{ReD}{(.658)^{2}-4(.00407)(0)}}}{ 2(.000407) }$ now just type the red part into the calculator

41. shaleiah

.432964

42. Nnesha

i just realized i'm the one who typed incorrectly sorry it's plus/minus $\frac{ -.658 \pm \sqrt{\color{ReD}{(.43296)}}}{ 2(.000407) }$

43. Nnesha

take the square root of .43296

44. shaleiah

oops

45. Nnesha

right so $\huge\rm \frac{ -.658+6.58 }{ 2(-.000407) } and \frac{ -.658-.658 }{ 2(-.000407) }$ now we can seprate plus and minus sign and i found another typo a=negative .000407

46. shaleiah

.6579969605

47. Nnesha

that is same as .658 remember the number after 7 is greater than 5 so you can round it

48. Nnesha

this post is solaggy

49. shaleiah

yeah, lots of lag :(

50. Nnesha

$\huge\rm \frac{ -.658+6.58 }{ 2(-.000407) } and \frac{ -.658-.658 }{ 2(-.000407) }$ alright work on this brb

51. shaleiah

Alright. I got 807545.4545

52. shaleiah

808

53. Nnesha

there are two fraction what did you get for first one what did you get for 2nd one

54. Nnesha

that doesn't looks right

55. Nnesha

use parenttheses

56. shaleiah

:c

57. Nnesha

what ?

58. shaleiah

are you sure the equation is set up correctly?

59. Nnesha

$\huge\rm \frac{ -.658+6.58 }{ 2(-.000407) } and \frac{ -.658-.658 }{ 2(-.000407) }$ yes this one is 100% correct

60. shaleiah

The first fraction is: -7275... The second fraction is: -807545

61. Nnesha

ugh first fraction is .658 -.658 not (6.58) 2nd fraction is 100% right but no ur answer is not right for 2nd one

62. Nnesha

tell me what did you type into the calculator for first fraction

63. shaleiah

The 6.58 was the error :(

64. Nnesha

$\huge\rm \frac{ -.658+.658 }{ 2(-.000407) }$ first one

65. shaleiah

0

66. Nnesha

67. Nnesha

hmm not correct what did you type into the caluclator ?

68. shaleiah

I'm sorry :/ I see the error. I re typed it and I got 1616.707617

69. Nnesha

yes that's right

70. shaleiah

Did we finish all the steps?

71. Nnesha

yep that's for 2nd part!

72. Nnesha

2nd one is how long so it would be 1616.71 0 wouldn't be the answer