## anonymous 5 years ago can i get some help from anyone dats good wit word problems

1. anonymous

2. anonymous

(h(t)=-16t^2+vt+c where h is the approximate height in ft t is the time in motion in seconds v is the initial upward velocity in ft per second and c is the initial height in ft) A baseball player hits a pitched ball when it is 4ft above the ground the initial upward velocity is 80ft/s how long will it take for the ball to hit the ground???

3. anonymous

Consider the given equation h(t)=-16t^2+vt+c. We are looking to find t, where v=80ft/s and c=4ft. h(t) represents the height when it hits the ground, that's h(t)=0. So: $0=-16t^2+80t+4 \implies -4t^2+20t+1=0$ Now solve the quadratic equation for t. Take only the positive value.

4. anonymous

how did u get the 2nd equation

5. anonymous

Divide both sides by 4.

6. anonymous

ok so how do i get t

7. anonymous

Use the quadratic formula. You will positive value t approximately 5.05 sec.

8. anonymous

will get*

9. anonymous

only answers it could be is 3s,4s or 2.2s cuz its one of those riddle papers

10. anonymous

11. anonymous

i though 4 was h

12. anonymous

>.< I don't know why 5 is not among the choices.

13. anonymous

im trippen it is 5.1 on here can u tell me how i can get it cuz idk how 2 do dis

14. anonymous

5.1 is there and you didn't say that? >.<

15. anonymous

yes and i didnt notice till i looked at the riddle paper

16. anonymous

:( I redid it like 6 times.

17. anonymous

im sorry

18. anonymous

can u still help me

19. anonymous

lol it's ok.. what is it that you don't understand?

20. anonymous

after i get t=-4t^2+20t+1 what do i do

21. anonymous

You just solve the equation for t. Are you allowed to use a calculator?

22. anonymous

yes

23. anonymous

but how u solve 4 t

24. anonymous

Okay, you can solve it by your calculator.

25. anonymous

i need steps

26. anonymous

$t={-b \pm \sqrt{b^2-4ac} \over 2a}={-20\pm \sqrt{20^2+16} \over -8}$

27. anonymous

or you can just write the equation in your calculator and it will give you the answer directly.

28. anonymous

i remember dat fromula but where u get -20 and -8

29. anonymous

a=4, b=20, c=1. Plug them in the equation.

30. anonymous

ok u have 2 understand i got like 11 more problems to do and im not understanding where u getting these numbers 4rm when it comes 2 math i gotta be talked 2 like im slow so i can pick it up quick u have 2 explain how u got a b c from dat word problem the only numbers i got from the equation is -16 80 and 4 so please explain

31. anonymous

okay, then take a=-16, b=80 and c=4. That will work exactly the same.

32. anonymous

y u make it so difficult u like my teacher just tell me the simple answer lol so do i use dat equation 4 all these problems

33. anonymous

hmm okay focus now.

34. anonymous

You told me you got the first equation. This is a quadratic equation, it can always be solved by the quadratic formula, which I wrote above. The question now is what a, b and c.

35. anonymous

ok hold on dis cant go in my calculator when it has the +-

36. anonymous

a is the coefficient of t^2, b is the coefficient of t, and c is the constant.

37. anonymous

just do it once with the minus, and another time with the plus.

38. anonymous

and then take from the two final answers, the positive one.

39. anonymous

wat was wrong with the formula they gave me dis is pissing me off

40. anonymous

I don't know!

41. anonymous

ok look can u tell me how to do it just using the formula they gave me i dont like dat other one it wont go in my calculator and im getting way 2 mad 2 focus

42. anonymous

43. anonymous

i did read wat u wrote but u not giving me step by step instructions may be natrual 2 u but it aint 2 me im good but slow at it so all i need is someone 2 break it down one good time instead of giving me alot of info without working it completly out

44. anonymous

45. anonymous

i dont know how to use h(t)=-16t^2+vt+c

46. anonymous

whoops you mean the very beginning? I don't think I can help you here. I am a little bit busy. I am so sorry. I really tried, but I might be not good at explaining things.

47. anonymous

ook

48. anonymous

Good luck!! :)

49. anonymous

i keep getteing 50.9 i finally figured out wat u was saying

50. anonymous

Good to know that :)

51. anonymous

can u help me e 5.1 answer cuz i guess im putting dis in the calculator wrog im not getting 5.1

52. anonymous

once i use the formula u gave me is there a step after dat 2 get the 5.1

53. anonymous

No, you have just to use your calculator correctly. Better to take it step by step, like start with the part under the square root.