Calculators An integral my Ti-89 refused to do

1. Sep 26, 2007

kidwithshirt

1. The problem statement, all variables and given/known data

Indefinite integral of sin(x)/(1+x^2)dx

2. Relevant equations

3. The attempt at a solution

2. Sep 26, 2007

HallsofIvy

Staff Emeritus
What reason do you have to believe that has an indefinite integral that can be written in terms of elementary functions?

3. Sep 26, 2007

kidwithshirt

i m sorry i dont really comprehend what you are trying to say here.

By the way my mistake on my behalf, it is the integral between the interval of -1 and 1

I dont know how to get started

4. Sep 26, 2007

Avodyne

This question has a very simple answer. Try graphing the function from -1 to 1 and you might see it.

5. Sep 26, 2007

kidwithshirt

i realized that in the first place, but is there a mathematical manipulation that could get the result?

6. Sep 26, 2007

Avodyne

Break the integral up into integrals from -1 to 0 and from 0 to 1. In the first, make a change of variable, x -> -x.

7. Sep 26, 2007

kidwithshirt

i dont understand what you are saying >.<

i started calc this year.

Could you show me your steps really quick

8. Sep 26, 2007

Avodyne

First tell me what the value of the integral is, and give your best explanation.

9. Sep 26, 2007

kidwithshirt

according to the graph it's 0 because the line is reflected on the origin so the two regions canceled each other out.

10. Sep 26, 2007

Avodyne

Yes, exactly. So the integral over the left half (from -1 to 0) must equal minus the integral over the right half (from 0 to 1).

Do you know how to change variables in an integral? You want to change the variable in the left-half integral from x to -x, and then show that the result is equal to minus the right-half integral.