Sup_open~study
i need some one to show me step by step how to do this /4c-2/, c= -3 it's Absolute value
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teic85
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plug in -3 for c, what do you get?
Sup_open~study
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let me see :)
Sup_open~study
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-14
?
Sup_open~study
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is that right ?
teic85
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right, the value of the expression inside the absolute value is -14. But, what does absolute value mean?
completeidiot
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examples of absolute value
|x|=x
|-z|=z
|100|=100
|-345|=345
etc etc etc
Sup_open~study
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i'm sorry an you explain more
teic85
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Do you know the definition of absolute value?
Sup_open~study
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i'm sorry i don't
Sup_open~study
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:(
teic85
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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.
Sup_open~study
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o ok so the "-3" is just a 3 and not a "-3 " so the answer would be 14
teic85
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You are half right...
teic85
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Let's back up...
teic85
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"-3" is still -3. That doesn't change. The problem says that c = -3. So, c = -3
teic85
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But, the problem says that you have to find /4c-2/ when c = -3
teic85
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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.
Sup_open~study
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o ok thanks man were did you get the ? /-12-/ + /-14? ?
teic85
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Where did I get -12???
Sup_open~study
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yeah :)
teic85
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-12 is the product of 4 and -3
teic85
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When you plug in -3 for c, you multiply 4 x -3
Sup_open~study
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o i see now wow xD thanks man for all of your help
teic85
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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
Sup_open~study
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ok awesome man thanks i will do :)
Hero
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|4c - 2|
Do you know how to use the shift button @teic85?
teic85
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No, how does that work?
Hero
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Hold down the shift button when pressing the \ key
teic85
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Oh I see, I was simply using the same notation as "sup"
teic85
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Thanks for pointing that out, though :)
Hero
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Hold down the shift button when trying to post || absolute value symbols
teic85
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Like this?
|4c-2|
Hero
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Precisely
teic85
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Thanks!
teic85
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Isn't there a keyboard shortcut for superscript too? Might come in handy for exponents
Sup_open~study
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i am stuck on this one -/-10-z,/z
=-3
Sup_open~study
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:(
Sup_open~study
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i got 30
Sup_open~study
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but i think it is wrong
teic85
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Ok, rewrite the expression after plugging in z = -3
teic85
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Also, use |, it's the key above the enter key. You must use the shift key
Sup_open~study
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-/10 (-3)/
like that ??
teic85
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Nope, you are using /. Press shift and \
Hero
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lol you're teaching people already @teic85
teic85
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And no, the expression is missing a minus
Sup_open~study
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i no clue what the shift thing is lol xD
teic85
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lol yes @Hero, that's the purpose of Open Study right? :D
Sup_open~study
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*have
Sup_open~study
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xD
Hero
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:D
teic85
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haha ok, @Sup_open~study . Let's focus on the problem first.
Sup_open~study
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i think i am so post to - it and not x it ?
teic85
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Correct, you have to subtract z not multiply
You wrote -/10 (-3)/
The original expression is -|-10-z|
teic85
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Be careful, you also missed the negative in front of the 10
Sup_open~study
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o i see yeah i was writing it wrong xD
teic85
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Rewrite the expression after plugging in -3 for z
Sup_open~study
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-/-10-3/ = 13 ?
teic85
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z = -3, but the expression is -10 MINUS z.
So, it should be -10 - (-3) which is actually -10 + 3
Sup_open~study
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so it's 7 ??
teic85
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What is 7?
You are jumping ahead... :)
Sup_open~study
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sorry xD
teic85
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haha it's ok :)
teic85
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When you plug in -3 for z, you get:
-|-10 - (-3)|
teic85
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That look about right to you?
Sup_open~study
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yeah thanks :)
teic85
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Ok, so we know that minus -3 is actually +3. So rewrite the entire expression with +3 in that spot
Sup_open~study
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ok so it's -|-10 - (3)|
Sup_open~study
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?
teic85
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Not quite,
Minus -3 is +3. So, it is -|-10+3|
teic85
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a negative and a negative make a positive
Sup_open~study
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o i see but how would i solve that ??
teic85
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ok, well now that that pesky z is gone, we can just focus on what is inside the absolute value. What is -10 + 3?
Sup_open~study
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- 7 so it's just 7 ?
teic85
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The absolute value of -7 is 7. Yes.
Sup_open~study
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o ok i see now but on the answer for the study guide he put -7 why not 7 ??
teic85
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What's in front of the absolute value?
Sup_open~study
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i can't tell what you are looking for sorry but he had like a -1 -10 + -7 ?
teic85
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This is the expression:
-|-10+3|. What is in front of the absolute value?
Sup_open~study
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a negative
Sup_open~study
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?
teic85
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Right
teic85
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So look at this...
|-7| = 7
What is -|-7| ?
Sup_open~study
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-7
Sup_open~study
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?
teic85
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Since the negative sign is in front, it makes the expression negative. So -7 is the answer.
teic85
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-|-7| is different than |-7|
Sup_open~study
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o so it's just 7
teic85
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No, it isn't just 7.
teic85
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The expression in your problem has a negative in front like this,
-|-7|
Sup_open~study
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yes
teic85
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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
Sup_open~study
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ok so when you have the - in front of the problem the answer is most likely going to be a - ???
teic85
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Don't think "most likely". You'll get the wrong answer. That's just guessing.
teic85
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Think about this...
what is -2(1 + 3) ?
Sup_open~study
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-8
teic85
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Right. The negative in front changes it to negative. So, when you have a positive number times a negative number you get a negative.
Sup_open~study
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o i see so when you change the answer to positive the negative will times it and that will make it an negative ?
teic85
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Yes
teic85
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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)
Sup_open~study
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o i see thanks man you have been a huge help i may have failed my test tomorrow if it was not for you
teic85
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I'm glad to help. Just be careful not to forget negatives. They matter a lot.
Sup_open~study
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yeah i know i got to keep on practicing those xD
teic85
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Exactly. If you practice, you'll get more comfortable. Eventually, you'll be able to do it in your head :)