SOLUTION: can you please help me solve this question, and explain what you did, my teacher didn't quite explain it well enough to me. |-3r|=9 Thank you!

Algebra ->  Absolute-value -> SOLUTION: can you please help me solve this question, and explain what you did, my teacher didn't quite explain it well enough to me. |-3r|=9 Thank you!      Log On


   

Question 806736: can you please help me solve this question, and explain what you did, my teacher didn't quite explain it well enough to me. |-3r|=9
Thank you!
Found 2 solutions by jim_thompson5910, Alan3354:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Use the idea that if |x| = k, then x = k or x = -k where k is some positive number.


So use that idea above to get....

|-3r|=9

-3r = 9 or -3r = -9

r = 9/(-3) or r = -9/(-3)

r = -3 or r = 3


Answers: r = -3 or r = 3

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
|-3r|=9
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Absolute value is the magnitude, or the distance from zero.
For this one, either
(-3r) = 9
or
-(-3r) = 9
There are 2 cases, so you get 2 answers.
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You can use = 9 or = -9, but be careful when it's an inequality.
Changing the sign of the values inside the ABS | | always works.