## anonymous 3 years ago Evaluate the following definite integral

1. anonymous

$\int\limits_{-1}^{2} \left| X \right| dx$

2. anonymous

I got 3/2 this is the wrong answer the correct answer is 2.5

3. hba

Can you show me your working ?

4. anonymous

$\left| x \right|$ $\frac{ x^2 }{ 2 }$ $(\frac{ 2^2 }{ 2 })- (\frac{ -1^2 }{ 2 })$ (4/2)-(1/2) 3/2

5. tkhunny

1) Convention suggests that $$X$$ is NOT the same as $$x$$. Please don't switch variable in the middle of a problem. 2) You have simply ignored the absolute value. That's no good. Split the integral at $$x = 0$$ and see if you can manage a different result.

6. anonymous

I'm still not sure what to do

7. anonymous

|dw:1358608829929:dw|

8. tkhunny

$$\int\limits_{-1}^{2}|x|\;dx = \int\limits_{-1}^{0}|x|\;dx + \int\limits_{0}^{2}|x|\;dx = \int\limits_{-1}^{0}(-x)\;dx + \int\limits_{0}^{2}(x)\;dx$$

9. anonymous

That should help

10. anonymous

thanks I will try that