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FR0568 #7

Posted: Sat Mar 27, 2010 4:58 am
by thmsrhn
Hey does one integrate the modulus of a function?

Here s the question:

integrate the mod of (X+1)dx whose upper and lower limits are 3 and -3 respectively.

Re: FR0568 #7

Posted: Sat Mar 27, 2010 11:27 am
by origin415
the modulus/absolute value is just
$$|a| = \begin{cases} a &a \geq 0 \\ -a &a < 0 \end{cases}$$

So your function |x+1| can actually be split into two normal functions, without any absolute values. Add the results of integrating them separately.

Re: FR0568 #7

Posted: Sun Sep 05, 2010 11:17 am
by mdornbos
The way I did this problem was to simply graph the function |x+1| from -3 to 3. You will notice that integrating this function creates two triangles. Then use the formula for area of a triangle and add up the two separate triangles areas to get the answer. I believe its (1/2*2*2) which is the triangle from x=-3 to x=-1, and (1/2*4*4) which is the triangle from x=-1 to x=3. Adding up the two areas you get 2+8=10.