Question about integration. (1 Viewer)

[ND]

Are you allowed to assume things like I 0-->a f(x)dx = I 0-->a f(a-x)dx, the odd and even properties etc.? Or do you have to prove them first?

 

[ezzy85]

im pretty sure you can assume it, but it would depend on the question. most questions ive seen that have these would lead you in by asking you to prove it or theyd be those true/false qs.

 

[ND]

Originally posted by ezzy85
im pretty sure you can assume it, but it would depend on the question. most questions ive seen that have these would lead you in by asking you to prove it or theyd be those true/false qs.

Well i was doing the 94 paper today, and it asked to show:

I 0-->pi/2 e^(-sinx)dx = I pi/2-->pi e^(-sinx)dx

Would i be allowed to use I 0-->a f(x)dx = I 0-->a f(a-x)dx without proving it first?

 

[freaking_out]

yeah, thats what i exactly asked my teacher....but she said no ur not allowed....rather u goto prove it....i haven't but have u checked the syllabus?? what does it say about that rule?

i guess if the syllabus says u need to know, then u can assume it.

 

[McLake]

If it is far enough removed from the quesion, then use it. Otherwise prove it ...

 

[ND]

Originally posted by McLake
If it is far enough removed from the quesion, then use it. Otherwise prove it ...

I'm not sure of what you mean, would i be allowed to assume it for the question posted above?

 

[McLake]

Originally posted by ND
I'm not sure of what you mean, would i be allowed to assume it for the question posted above?

I don't think so. But if it was a volumes (for instance) question, and it required that fact, then you could probably use it

 

[OLDMAN]

Student's attitude toward examiners should be : Examiners are fair, bonza and dinkum!

Working from that attitude, students should be fair, bonza and dinkum back.

ND : just do it!
sub y=pi-x
I (0-->pi/2) e^(-sinx)dx = -I (pi--->pi/2) e^(-siny)dy
=I (pi/2-->pi) e^(-sinx)dx

Now that didn't take longer than having to decide whether to do it or not, did it?