## brittany_lundgren Group Title 1.Solve S = 4v2 for v. Show your work 2 years ago 2 years ago

1. inkyvoyd Group Title

Wel, first isolate the term for v^2

2. inkyvoyd Group Title

*first isolate v^2

3. inkyvoyd Group Title

(divide by 4, if you don't know)

4. brittany_lundgren Group Title

ok

5. inkyvoyd Group Title

S/4=v^2

6. brittany_lundgren Group Title

ok

7. inkyvoyd Group Title

Then, take the plus-minus square root of both sides.

8. inkyvoyd Group Title

You know how to simplify $$\Huge \pm\sqrt\frac{S}{4}$$ right?

9. brittany_lundgren Group Title

ok im following you

10. inkyvoyd Group Title

Let me show you the whole thing. ONe sec, this may take a minute or two.

11. brittany_lundgren Group Title

ok im waiting :)

12. inkyvoyd Group Title

S = 4v2 $$\Large S=4v^2$$ ->Isolate the "$$v^2$$" $$\Large \frac{S}{4}=v^2$$ Take the positive negative square root of both sides $$\huge \pm\sqrt{\frac{S}{4}}=v$$ $$\huge \pm\frac{\sqrt{S}}{\sqrt{4}}=v$$ Can you try from here?

13. inkyvoyd Group Title

@brittany_lundgren ?

14. brittany_lundgren Group Title

I can try........ I dont remember how to do any of ths... I'm sooo lost!

15. inkyvoyd Group Title

Alright, it's ok. Just tell me which steps you don't understand :)

16. brittany_lundgren Group Title

I honestly need help with the whole problem, im soooo confused! :'(

17. inkyvoyd Group Title

Ok, so, from step one, right? Which parts of step one do you not understand? Or is it the problem itself?

18. brittany_lundgren Group Title

It's the problem itself, I just don't understand :'(

19. inkyvoyd Group Title

Ok, what they do is give you an equation. What they want you to do is to "solve for v" This means they want you to put v on one side, and everything else on the other.

20. inkyvoyd Group Title

Note that v can ONLY be on one side. If you have v on both sides, it's a mistake.

21. brittany_lundgren Group Title

okay, im following you so far!

22. inkyvoyd Group Title

Good. :)

23. jhonyy9 Group Title

i have solved it before - not is clearly there ?

24. inkyvoyd Group Title

Now, do you remember how we move things around?

25. inkyvoyd Group Title

Like, combine like terms, move things from one side to the other, and take square roots?

26. brittany_lundgren Group Title

ok well can you show me how? Like the steps ??

27. inkyvoyd Group Title

Ok. In general, or just for this equation?

28. brittany_lundgren Group Title

just the steps on how to solve this problem... The problem told me to show my work.......

29. inkyvoyd Group Title

Okk.

30. inkyvoyd Group Title

Remember, we want to put "v" on one side, and everything else on the other. The first step is to get rid of what's in front of v.

31. brittany_lundgren Group Title

okay so what would I do then?

32. inkyvoyd Group Title

What's in front of v?

33. brittany_lundgren Group Title

1.Solve S = 4v2 for v.

34. inkyvoyd Group Title

I mean, what's in front of "v^2"?

35. brittany_lundgren Group Title

4

36. inkyvoyd Group Title

So, how do we move the 4 to the other side?

37. brittany_lundgren Group Title

-4(4-4)=-2(2v-1)

38. inkyvoyd Group Title

Not that complicated. Just divide both sides by 4 :)

39. brittany_lundgren Group Title

Is the answer to the question v=2?

40. inkyvoyd Group Title

Well, we can't actually solve for an exact value of v. We can only express it in terms of "s".

41. brittany_lundgren Group Title

okay, I'm sooo confused!!! :'(

42. inkyvoyd Group Title

Ok. We can't always solve for v (in terms of a number, like 3, or -2). But, we can move everything over to one side and leave v on the other.

43. brittany_lundgren Group Title

OMG!!! dumb right now :(

44. inkyvoyd Group Title

Ok. If you have the equation x-2y=0 you can't find x, because you don't know y.

45. brittany_lundgren Group Title

okay, I understand that, I just don''t understand on how to solve this problem!

46. inkyvoyd Group Title

Ok. Solve for v doesn't mean "get a number value for v". It means, "put just v on one side, and everything else without v on the other"

47. brittany_lundgren Group Title

ok,im following so far.

48. inkyvoyd Group Title

Alright. Since we just want to move everything to the other side, we divide both sides by 4 to get rid of what's in front of v.

49. brittany_lundgren Group Title

ok so S/4=4v^2/4

50. inkyvoyd Group Title

Ok. Now simplify the rigt side.

51. brittany_lundgren Group Title

S=v^2

52. inkyvoyd Group Title

Careful, you can't cancel out the left side...

53. brittany_lundgren Group Title

S/4=v^2

54. inkyvoyd Group Title

yess.

55. inkyvoyd Group Title

Now, what do we do to get rid of v^2? (turn it into v)

56. brittany_lundgren Group Title

S/4=v

57. inkyvoyd Group Title

Careful. You have to take the square root of BOTH sides.

58. brittany_lundgren Group Title

I got confused, just now. I beeen following this whole time and i just now got lost!!! :'(

59. inkyvoyd Group Title

That's ok.

60. inkyvoyd Group Title

S/4=4v^2/4 -> $$\huge \frac{S}{4}=\frac{(4v^2)}{4}$$

61. inkyvoyd Group Title

Then $$\Huge \frac{S}{4}=v^2$$

62. inkyvoyd Group Title

Now, here's the part you got lost. Let me show it in more detail.

63. inkyvoyd Group Title

$$\Huge \pm\sqrt{\frac{S}{4}}=\sqrt{v^2}$$

64. inkyvoyd Group Title

There's a lot going on right here.

65. inkyvoyd Group Title

Does everything make sense?

66. brittany_lundgren Group Title

ima little lost there

67. inkyvoyd Group Title

Ok. Do you know why we have the plus minus sign?

68. brittany_lundgren Group Title

nope, im confused whole step.......

69. inkyvoyd Group Title

I'm really sorry, but I have to go to bed. I'll try to make sure I get people here to help you. (I have to take some tests myself tomorrow, and I can't afford to miss them) @nbouscal , would you be so kind as to help out? THanks.

70. brittany_lundgren Group Title

damn, what time is it there?

71. inkyvoyd Group Title

2:00 AM. I have to go to sleep and get done before 2:00PM, but I have two tests around 1 hour each, :S

72. brittany_lundgren Group Title

dang........

73. inkyvoyd Group Title

ACtually, I'm going to take both right now. No chances.

74. inkyvoyd Group Title

Time for a cup of coffee. thanks, @nbouscal .

75. nbouscal Group Title

Okay, if you have $$v^2=\frac{S}{4}$$, and you want to know what $$v$$ is, you have to take the square root of both sides. That's the only way to get the left side to just have $$v$$ by itself. The problem is, when you square root something, you always have to put a $$\pm$$ sign in front, because you don't know whether it's positive or negative. For example, $$2^2=4, (-2)^2=4$$, so the square root of 4 could be either 2 or -2. So, we take the square root of both sides and we add a plus-or-minus, and we get $v=\pm\sqrt{\frac{S}{4}}$

76. brittany_lundgren Group Title

@nbouscal brb imma go get something to drink

77. brittany_lundgren Group Title

ok, im following so far.

78. inkyvoyd Group Title

Brittany, I can help too, becaues I just realized I only have one test.

79. inkyvoyd Group Title

$$\huge v=\pm\frac{\sqrt{S}}{\sqrt{4}}$$

80. inkyvoyd Group Title

Remember, $$\Huge \sqrt{\frac{a}{b}}=\frac{\sqrt{a}}{\sqrt{b}}$$

81. inkyvoyd Group Title

Now, what's the square root of 4?

82. inkyvoyd Group Title

(@nbouscal , I'm going to go ahead and take my scantron before the coffee wears off)

83. brittany_lundgren Group Title

2

84. brittany_lundgren Group Title

@inkyvoyd @nbouscal

85. inkyvoyd Group Title

Ok, then, what do we get?

86. inkyvoyd Group Title

(use draw if you have to)

87. nbouscal Group Title

$$v=\pm\dfrac{\sqrt{S}}{\sqrt{4}}$$, $$\sqrt{4}=2$$, so $$v=?$$

88. inkyvoyd Group Title

@brittany_lundgren , do you get it?