# Find the cdf given a pdf with absolute value

## Homework Statement

Consider a continuous random variable X with the probability density function fX(x) = |x|/5 , – 1 ≤ x ≤ 3, zero elsewhere.
I need to find the cumulative distribution function of X, FX (x).

2. Homework Equations

The equation to find the cdf.

## The Attempt at a Solution

FX(x) = ∫-1x -u/5 du + ∫-10 -u/5 du + ∫0x u/5 du

For some reason, my result is just a constant, but I can't figure out why my equation is wrong?

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LCKurtz
Homework Helper
Gold Member

## Homework Statement

Consider a continuous random variable X with the probability density function fX(x) = |x|/5 , – 1 ≤ x ≤ 3, zero elsewhere.
I need to find the cumulative distribution function of X, FX (x).

2. Homework Equations

The equation to find the cdf.

## The Attempt at a Solution

FX(x) = ∫-1x -u/5 du + ∫-10 -u/5 du + ∫0x u/5 du

For some reason, my result is just a constant, but I can't figure out why my equation is wrong?
You have to do two cases. First take ##-1\le x \le 0## and work that. You will just need one integral. Then take ##x>0## and work that, which will take two integrals with ##x## only in the second one, etc.

Oh I understand, the solution will have two cases. Thank you!

LCKurtz