## sara1234 2 years ago HELP ME PLZ

1. seiga

why dont u use mathway.com it helps?!

2. sara1234

i know how to do this but i don't know why i keep getting a wrong answer?

3. seiga

okay what did u get....go step by step.?

4. sara1234

i got this 1.5159=(4+r)^(44)

5. seiga

hold on lemme see...

6. seiga

i think its 3.8

7. sara1234

can you show me what you did ?

8. seiga

i was guessing lmao i hate math!

9. seiga

sorry:/

10. seiga

wait i think i got it....wait

11. sara1234

what you get?

12. sara1234

anyone can show me how to solve this? 2976.45=1963.45(1+r/4)^4(11)

13. tcarroll010

You have an equation of the form: a = b(x^n) That will equal: a/b = x^n -> ln(a/b) = ln(x^n) -> ln(a/b) = n times ln(x) [ln(a/b)] / n = ln (x) e^( [ln(a/b)] / n ) = e^[ln(x)] = x "x" is your expression in parentheses, the 1 + a quarter of the rate.

14. sara1234

what is that?? the formula i wrote is correct

15. tcarroll010

Yes, your formula is correct and it matches mine. I am just using a general symbol method. For you to do some work here, you only have to make the substitutions and solve.

16. sara1234

i dont understand that can you please just show me how to solve that formula i did it several times and got a wrong answer PLEASEE i beg you im so tired

17. tcarroll010

You can do this! 2976.45=1963.45(1+r/4)^4(11) a = 2976.45, b = 1963.45, n = 44 Just make those substitutions and follow my solution method. Just plug in and follow the steps. Just try it. If you are that tired, I can give you a little more, but we tutors can't just give answers, we are required to show students how to solve and and top of it the students are supposed to do the work. I'll help as much as I can, but I can't just give ans answer.

18. tcarroll010

Start by dividing both sides by what "b" is. It will start to isolate that exponential expression on the right-hand side.

19. sara1234

i didd this many timessss im telling youu i just want to see where i went wrong i end up with 1.5159=5+r

20. sara1234

^44

21. sara1234

1.5159=(1+r/4)^4*11

22. sara1234

then- 1.5159=5+r^44 im not sure about 5 than what do i doo

23. tcarroll010

Good so far, keep going.

24. tcarroll010

Wait, hold on.

25. tcarroll010

This is where you went wrong. And before I show you, I just quickly want to say that doing it this way, you will learn. If I just did the steps, no way is anyone going to learn. This is learning by mistakes. Don't be afraid of mistakes. Now, The (1 + r/4) has to stay in parentheses for quite a while. Always respect the parentheses. They take precedence over the exponentiation. If you don't like that long expression in parentheses, call it "x" for now.

26. tcarroll010

So, I'll take over from here for a little while and give you a little break. Hold on while I type.

27. tcarroll010

1.5159286 = (1 + r/4)^44 ln 1.5159286 = ln [(1 + r/4)^44] = 44 times ln [(1 + r/4)] (ln 1.5159286) / 44 = ln [(1 + r/4)] e^[(ln 1.5159286) / 44] = e^(ln [(1 + r/4)]) = (1 + r/4)

28. tcarroll010

Are you still getting this or did you get lost anywhere along the way? Should I stop or go on?

29. sara1234

i dont understand the way you type i have all the steps in my paper can you just give me the second to last line of this problem so i can see if its the same i get 1.0094=4+r

30. sara1234

then i have to take away 4 from each side

31. sara1234

i keep getting an negative number

32. tcarroll010

ok, we'll do it that way. Hold on.

33. sara1234

1.5159^1/44=4+r^1/44 this is where i can stuck putting it to the power of ^1/44 i get 1.0094 which idk is right or not please help me fast its late

34. tcarroll010

e^[(ln 1.5159286) / 44] = e^(ln [(1 + r/4)]) = (1 + r/4) e^[(ln 1.5159286) / 44] - 1 = r/4 4(e^[(ln 1.5159286) / 44] - 1) = r The right side is the rate. The left side is: 0.03800011 That's 3.8%

35. tcarroll010

That's the annual rate. It's 4 times the quarterly rate of: 0.9500028 percent.

36. sara1234

so where did i go wrong

37. tcarroll010

I know it's late and you're tired, so tomorrow, you might want to go over all of this. I strongly recommend this. Good working with you and thx for the recognition. More importantly, just hang in there! You went wrong by taking that 1 + r/4 out of the parentheses. That stays in there until the very end.

38. tcarroll010

Fast? It's going to take me a while just to read it!

39. sara1234

thats fine

40. tcarroll010

Well, I got problem #11, it's "b", not "c" like you have it, but you were not far off.

41. sara1234

thanks

42. tcarroll010

#12 is quarterly, not monthly. I don't think you are getting this just yet. You need to practice this a lot more.

43. sara1234

these are practice problem i did like 50 and these are the ones i wasnt sure about

44. sara1234

i just want to know which ones i need to practice more

45. sara1234

how are 13 and 14 last two?

46. sara1234

im sure about the rest just not these 4

47. tcarroll010

You had #11 and #12 wrong and I got you right answers. I figured out #13 (didn't look at #14 yet). I need to see your work since you are not getting these right. Show me your work on #13.

48. sara1234

my work is on paper its going to take me a while to type but i think 13 is okay

49. tcarroll010

Yes, #13 is definitely 88.

50. sara1234

for 14 i think its wrong

51. tcarroll010

What is "n" and "an"? I don't get what those expressions mean. To do this problem, I need to know what "n" and "an" stand for.

52. sara1234

thats what im trying to figure out

53. tcarroll010

Not the values, what is the meaning of "n" and "an"? They stand for something even before we figure out the values.

54. sara1234

i think n is number of cells and an is days or vise versa thats what im trying to figure out

55. sara1234

i'll just go with A

56. tcarroll010

Hold, on I figured it out algebraically.

57. tcarroll010

I'm just trying to relate my answer back to the crazy notation in the problem.

58. tcarroll010

You're going to have to help with relating the answer back to the problem's notation, but here it is in how I look at it: For any day, starting with the 3rd day, that day's number of cells is: [2 x (# cells in previous day)] - (# cells in previous to previous day) + 3 "previous day" is "day - 1" "previous to previous day" is "day - 2" Making sense?

59. sara1234

yeah

60. tcarroll010

I checked this answer out up to 88, which is day 7. Can you get this back into that crazy notation?

61. sara1234

not really other than -1

62. tcarroll010

Well, I know my formula works like a charm. We could try together to get that into the notation from the problem, but I still don't know about that "an" and "n". Are you sure that that problem was written down right?

63. tcarroll010

While you're answering that, I'm working on that notation.

64. sara1234

its A for sure thanks for your help

65. tcarroll010

Yes, I just confirmed A. I figured out the notation, but you might want a bit of explanation on it.

66. tcarroll010

I don't know where that post of yours went, I don't see it anymore, but A was correct, for sure.

67. tcarroll010

Well! It looks like we're done! Nice working with you and good luck in everything!

68. sara1234

Your so nice thank you so much please keep in touch please

69. tcarroll010

And you're nice, too! You made my day! :-)

70. tcarroll010

btw, "an - 1" is the # of cells in the previous day, but I think you know that by now.

71. tcarroll010

And this was exhausting!