My Math Forum  

Go Back   My Math Forum > College Math Forum > Calculus

Calculus Calculus Math Forum


Thanks Tree3Thanks
  • 2 Post By romsek
  • 1 Post By romsek
Reply
 
LinkBack Thread Tools Display Modes
July 25th, 2019, 07:02 AM   #1
Newbie
 
Joined: Nov 2018
From: Iran

Posts: 12
Thanks: 0

Math Focus: calculus
double integral

Hello ,anyone got an idea about getting the area of the place surrounded by
y=-x^2+x and y=-x by double integrals .
really thanks by the way
Attached Images
File Type: jpg Capture.jpg (14.5 KB, 8 views)
shadow dancer is offline  
 
July 25th, 2019, 07:29 AM   #2
Senior Member
 
romsek's Avatar
 
Joined: Sep 2015
From: USA

Posts: 2,585
Thanks: 1430

$I = \displaystyle \int_0^2 \int_{-x}^{x-x^2}~dy~dx$
Thanks from topsquark and shadow dancer
romsek is online now  
July 25th, 2019, 10:18 PM   #3
Newbie
 
Joined: Nov 2018
From: Iran

Posts: 12
Thanks: 0

Math Focus: calculus
Quote:
Originally Posted by romsek View Post
$I = \displaystyle \int_0^2 \int_{-x}^{x-x^2}~dy~dx$
You've got any idea about the notation
shadow dancer is offline  
July 25th, 2019, 11:01 PM   #4
Senior Member
 
romsek's Avatar
 
Joined: Sep 2015
From: USA

Posts: 2,585
Thanks: 1430

Quote:
Originally Posted by shadow dancer View Post
You've got any idea about the notation
what do you mean?
romsek is online now  
July 26th, 2019, 12:14 AM   #5
Newbie
 
Joined: Nov 2018
From: Iran

Posts: 12
Thanks: 0

Math Focus: calculus
Quote:
Originally Posted by romsek View Post
what do you mean?
Notation like f(x,y) kind of thing. Or it's not needed?

Last edited by skipjack; August 1st, 2019 at 09:48 AM.
shadow dancer is offline  
July 26th, 2019, 06:40 AM   #6
Senior Member
 
romsek's Avatar
 
Joined: Sep 2015
From: USA

Posts: 2,585
Thanks: 1430

Quote:
Originally Posted by shadow dancer View Post
Notation like f(x,y) kind of thing. Or it's not needed?
It's a definite integral. It's not a function of $x$ and $y$. Those just serve as dummy variables for the integral.
Thanks from ProofOfALifetime

Last edited by skipjack; August 1st, 2019 at 09:49 AM.
romsek is online now  
August 1st, 2019, 08:49 AM   #7
Newbie
 
Joined: Nov 2018
From: Iran

Posts: 12
Thanks: 0

Math Focus: calculus
So the integral is wrong? I mean, is there no way of calculating that area with double integral?

Last edited by skipjack; August 1st, 2019 at 09:47 AM.
shadow dancer is offline  
August 1st, 2019, 08:54 AM   #8
Senior Member
 
romsek's Avatar
 
Joined: Sep 2015
From: USA

Posts: 2,585
Thanks: 1430

Quote:
Originally Posted by shadow dancer View Post
So the integral is wrong? I mean, is there no way of calculating that area with double integral?
Where did you get that idea?

I just said that the integral as given is a definite number.

It's not a function of x or y.

Last edited by skipjack; August 1st, 2019 at 09:47 AM.
romsek is online now  
August 1st, 2019, 09:51 AM   #9
Global Moderator
 
Joined: Dec 2006

Posts: 21,028
Thanks: 2259

Quote:
Originally Posted by shadow dancer View Post
Notation like f(x,y) kind of thing.
The two functions mentioned in the question were used as integration limits.
skipjack is offline  
Reply

  My Math Forum > College Math Forum > Calculus

Tags
double, integral



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
double integral Lobinho Calculus 1 July 4th, 2015 06:03 AM
Double integral, repeated integral and the FTC Jhenrique Calculus 5 June 30th, 2015 03:45 PM
integral of double integral in a region E maximus101 Calculus 0 March 4th, 2011 01:31 AM
need help with double integral greyjay Calculus 2 October 27th, 2008 06:49 PM
integral of double integral in a region E maximus101 Algebra 0 December 31st, 1969 04:00 PM





Copyright © 2019 My Math Forum. All rights reserved.