How do you solve the absolute value equation x+absx=28?

2 Answers
Apr 1, 2015

If x<0, the abs(x)=-x and x+absx = 0 !=28 so we must have x>0 and absx = x so we need x+x=28 and x=14

Apr 1, 2015

Answer is x = 14

To solve this equation you need to understand what |x|
means.
The Magnitude of x (denoted |x|) simply means the positive side of a number(x)

If x is positive or 0 (x>=0) then |x| = x
and if x is negative (x<0) it imples |x| = -x

Example:
|5| = 5 because 5 is already positive
|-11| = -(-11) because -11 is negative

Back to our question:
x + |x| = 28

There will be at most two values of x, because there are two possibilities; either x >=0 or x<0

Case 1: x>=0
=> x + x = 28

=> 2x = 28 => x = 14

Case 2: x<0
=> x - x = 28 => 0 = 28
but we know that 0!= 28 So the above(last) statement is inconclusive

So the only value we can retain is x = 14