Questions on Algebra: Functions, Domain, NOT graphing answered by real tutors!

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Question 152606: write |x| as a piecewise function.: write |x| as a piecewise function.
Answer by mducky2(55) About Me  (Show Source):
You can put this solution on YOUR website!
Let's write |x| as a function:
f(x) = |x|

Let's solve for f(x) when x > 0. We know that for all x > 0, the absolute value doesn't change anything, since x is already positive. Therefore:
For x > 0, f(x) = x

We also know that for all x < 0, the absolute value makes the negative number positive again. Multiplying the negative number x with -1 has the same effect, so:
For x < 0, f(x) = -x

Now we need to know f(x) when x = 0.
f(x) = |0| = 0
The number didn't change. Therefore:
For x = 0, f(x) = x

Combining everything together:
The piecewise function of f(x) = |x| is
for x >= 0, f(x) = x
for x < 0, f(x) = -x
Question 152606: write |x| as a piecewise function.: write |x| as a piecewise function.
Answer by jim_thompson5910(9166) About Me  (Show Source):