## Sup_open~study 3 years ago i need some one to show me step by step how to do this /4c-2/, c= -3 it's Absolute value

1. teic85

plug in -3 for c, what do you get?

2. Sup_open~study

let me see :)

3. Sup_open~study

-14 ?

4. Sup_open~study

is that right ?

5. teic85

right, the value of the expression inside the absolute value is -14. But, what does absolute value mean?

6. completeidiot

examples of absolute value |x|=x |-z|=z |100|=100 |-345|=345 etc etc etc

7. Sup_open~study

i'm sorry an you explain more

8. teic85

Do you know the definition of absolute value?

9. Sup_open~study

i'm sorry i don't

10. Sup_open~study

:(

11. teic85

Absolute value is the numerical value of a number without considering the positive or negative sign. So, the absolute value of 10 is 10. The absolute value of -2 is 2. It is just the value of the number. It is always positive.

12. Sup_open~study

o ok so the "-3" is just a 3 and not a "-3 " so the answer would be 14

13. teic85

You are half right...

14. teic85

Let's back up...

15. teic85

"-3" is still -3. That doesn't change. The problem says that c = -3. So, c = -3

16. teic85

But, the problem says that you have to find /4c-2/ when c = -3

17. teic85

So, plug in -3 for c just like you did before, /4(-3)-2/ = /-12-2/ = /-14/ So, when you plug in -3 for c, the expression equals /-14/. But, the absolute value of -14 is 14.

18. Sup_open~study

o ok thanks man were did you get the ? /-12-/ + /-14? ?

19. teic85

Where did I get -12???

20. Sup_open~study

yeah :)

21. teic85

-12 is the product of 4 and -3

22. teic85

When you plug in -3 for c, you multiply 4 x -3

23. Sup_open~study

o i see now wow xD thanks man for all of your help

24. teic85

You're welcome. If you have time, try these to make sure you know how to do absolute values: Find /4c-2/ when c = 3 Find 4/c/-2 when c = -3 Find 4c - /-2/ when c = -3

25. Sup_open~study

ok awesome man thanks i will do :)

26. Hero

|4c - 2| Do you know how to use the shift button @teic85?

27. teic85

No, how does that work?

28. Hero

Hold down the shift button when pressing the \ key

29. teic85

Oh I see, I was simply using the same notation as "sup"

30. teic85

Thanks for pointing that out, though :)

31. Hero

Hold down the shift button when trying to post || absolute value symbols

32. teic85

Like this? |4c-2|

33. Hero

Precisely

34. teic85

Thanks!

35. teic85

Isn't there a keyboard shortcut for superscript too? Might come in handy for exponents

36. Sup_open~study

i am stuck on this one -/-10-z,/z =-3

37. Sup_open~study

:(

38. Sup_open~study

i got 30

39. Sup_open~study

but i think it is wrong

40. teic85

Ok, rewrite the expression after plugging in z = -3

41. teic85

Also, use |, it's the key above the enter key. You must use the shift key

42. Sup_open~study

-/10 (-3)/ like that ??

43. teic85

Nope, you are using /. Press shift and \

44. Hero

lol you're teaching people already @teic85

45. teic85

And no, the expression is missing a minus

46. Sup_open~study

i no clue what the shift thing is lol xD

47. teic85

lol yes @Hero, that's the purpose of Open Study right? :D

48. Sup_open~study

*have

49. Sup_open~study

xD

50. Hero

:D

51. teic85

haha ok, @Sup_open~study . Let's focus on the problem first.

52. Sup_open~study

i think i am so post to - it and not x it ?

53. teic85

Correct, you have to subtract z not multiply You wrote -/10 (-3)/ The original expression is -|-10-z|

54. teic85

Be careful, you also missed the negative in front of the 10

55. Sup_open~study

o i see yeah i was writing it wrong xD

56. teic85

Rewrite the expression after plugging in -3 for z

57. Sup_open~study

-/-10-3/ = 13 ?

58. teic85

z = -3, but the expression is -10 MINUS z. So, it should be -10 - (-3) which is actually -10 + 3

59. Sup_open~study

so it's 7 ??

60. teic85

What is 7? You are jumping ahead... :)

61. Sup_open~study

sorry xD

62. teic85

haha it's ok :)

63. teic85

When you plug in -3 for z, you get: -|-10 - (-3)|

64. teic85

That look about right to you?

65. Sup_open~study

yeah thanks :)

66. teic85

Ok, so we know that minus -3 is actually +3. So rewrite the entire expression with +3 in that spot

67. Sup_open~study

ok so it's -|-10 - (3)|

68. Sup_open~study

?

69. teic85

Not quite, Minus -3 is +3. So, it is -|-10+3|

70. teic85

a negative and a negative make a positive

71. Sup_open~study

o i see but how would i solve that ??

72. teic85

ok, well now that that pesky z is gone, we can just focus on what is inside the absolute value. What is -10 + 3?

73. Sup_open~study

- 7 so it's just 7 ?

74. teic85

The absolute value of -7 is 7. Yes.

75. Sup_open~study

o ok i see now but on the answer for the study guide he put -7 why not 7 ??

76. teic85

What's in front of the absolute value?

77. Sup_open~study

i can't tell what you are looking for sorry but he had like a -1 -10 + -7 ?

78. teic85

This is the expression: -|-10+3|. What is in front of the absolute value?

79. Sup_open~study

a negative

80. Sup_open~study

?

81. teic85

Right

82. teic85

So look at this... |-7| = 7 What is -|-7| ?

83. Sup_open~study

-7

84. Sup_open~study

?

85. teic85

Since the negative sign is in front, it makes the expression negative. So -7 is the answer.

86. teic85

-|-7| is different than |-7|

87. Sup_open~study

o so it's just 7

88. teic85

No, it isn't just 7.

89. teic85

The expression in your problem has a negative in front like this, -|-7|

90. Sup_open~study

yes

91. teic85

So, the absolute value of -7 is 7. But, then you have to add the final negative (the one in front). So, it's -7

92. Sup_open~study

ok so when you have the - in front of the problem the answer is most likely going to be a - ???

93. teic85

Don't think "most likely". You'll get the wrong answer. That's just guessing.

94. teic85

95. Sup_open~study

-8

96. teic85

Right. The negative in front changes it to negative. So, when you have a positive number times a negative number you get a negative.

97. Sup_open~study

o i see so when you change the answer to positive the negative will times it and that will make it an negative ?

98. teic85

Yes

99. teic85

The same is true for absolute values. The negative in front of -|-7| is like multiplying -1 times |-7| (what your teacher had in your notes)

100. Sup_open~study

o i see thanks man you have been a huge help i may have failed my test tomorrow if it was not for you

101. teic85

I'm glad to help. Just be careful not to forget negatives. They matter a lot.

102. Sup_open~study

yeah i know i got to keep on practicing those xD

103. teic85

Exactly. If you practice, you'll get more comfortable. Eventually, you'll be able to do it in your head :)