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View Full Version : probably simple but important calculus problem

rachelspi
November 12th 2008, 08:23 AM
ok, so i have been ignoring this one thing that i have not managed to learn, and or can not find easily.

when you have a joint distribution, how do you determine the limits of integration. i never no if it is from zero to x or zero to 1 or what. it always confuses me.

i have tried paulīs online math notes (very good and FREE!) and two calc books but i seem to be missing that part. so any help you can provide would be great.

thanks!!!

:geek:

NoMoreExams
November 12th 2008, 01:37 PM
ok, so i have been ignoring this one thing that i have not managed to learn, and or can not find easily.

when you have a joint distribution, how do you determine the limits of integration. i never no if it is from zero to x or zero to 1 or what. it always confuses me.

i have tried paulīs online math notes (very good and FREE!) and two calc books but i seem to be missing that part. so any help you can provide would be great.

thanks!!!

:geek:

ALWAYS draw a picture, do you have an example in mind you want to work through?

rachelspi
November 13th 2008, 06:02 AM
ok, so maybe my problem is drawing pictures...

but the problem is this:

f(x,y) = 2x^2 + 3y

and i have to solve for fx (x) and fy (y). i just donīt get why the limits are from 1 to zero. i mean, i know that when you draw the graph you should take the outer bounds. in the meantime i am going to look up how to draw graphs.

rachel

NoMoreExams
November 13th 2008, 07:59 AM
ok, so maybe my problem is drawing pictures...

but the problem is this:

f(x,y) = 2x^2 + 3y

and i have to solve for fx (x) and fy (y). i just donīt get why the limits are from 1 to zero. i mean, i know that when you draw the graph you should take the outer bounds. in the meantime i am going to look up how to draw graphs.

rachel

If you are given that joint pdf, you should be given some limits for x and y, what are they?