SOLUTION: how do you slove them and how do you know if they are a solution or not? |r-8|=5

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Question 399759: how do you slove them and how do you know if they are a solution or not?
|r-8|=5
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
This symbol |x| denotes the absolute value of x. That is the number without its sign, like |+3| = 3 and |-3| = 3.
|r-8|=5......absolute value equation

Solve for x:
|r - 8| = 5
Solution:

r+-8 is the argument. Either that argument will be 5, or it will be -5.
r+-8+=+5, or r+-8+=+-5
We must solve these two equations. The first implies
r+-8+=+5
r+=+5%2B8
r+=+13
The second implies
r+-8+=+-5
r+=+-5%2B8
r+=+3
These are the two solutions: r+=+13 or 3.