How do you solve #abs(-3r)=9#?

2 Answers
Apr 12, 2018

Answer:

#r=3#

Explanation:

Those bars around the #-3r# are called absolute value bars and they turn everything inside positive, after they are in base form that is:
Ex: #|3-10|=x# ; #|-7|=x#; #x=7#
For this problem the #-3r# is going to get turned positive:
#|-3r|=9# ; #3r=9#
Than divide the #3#:
#r=3#

Apr 12, 2018

Answer:

#r=-3,3#

Explanation:

When you have an absolute value like this, you can set #-3r=9# and #-3r=-9#.

Solve both equations by dividing both sides by -3 and get #r=-3,3#.

If you want to check, try plugging -3 and 3 back into the original equation #abs(-3r)=9#.
It works out: #abs(-3(-3))=9# and #abs(-3(3))=9#.