Double (Iterated) Integration. Where am I going wrong?

  • Thread starter Thread starter skaterbasist
  • Start date Start date
  • Tags Tags
    Integration
Click For Summary
SUMMARY

The discussion focuses on solving a double (iterated) integration problem involving the region D defined by the curves x = (y^2) - 9 and x = 2y - 6, with the surface z = 1y^2. The user initially calculated an incorrect volume of -179975.2 due to mislabeling the intersection points of the curves. Correcting the limits of integration from 16 to -9 and adjusting the intersection points led to the accurate solution.

PREREQUISITES
  • Understanding of double integration and iterated integrals
  • Familiarity with Fubini's Theorem
  • Knowledge of the Fundamental Theorem of Calculus
  • Ability to graph and analyze curves in the Cartesian plane
NEXT STEPS
  • Review the application of Fubini's Theorem in double integrals
  • Practice finding intersection points of curves in the Cartesian plane
  • Learn how to correctly set limits of integration for iterated integrals
  • Explore common mistakes in calculating volumes under surfaces
USEFUL FOR

Students studying calculus, particularly those focusing on double integration and volume calculations, as well as educators looking for examples of common errors in iterated integration problems.

skaterbasist
Messages
13
Reaction score
0

Homework Statement



Let D be the region in the x,y-plane enclosed by the curves x = (y^2) - 9 and x = 2y - 6. Find the volume of the solid with base D that lies under the surface z = 1y^2.

Homework Equations



Fubini's Theorem and Fundamental Theorem of Calculus

The Attempt at a Solution



Hello everyone,

I need some help with a simple iterated integration. I just can't seem to figure out where I am going wrong. According to an online homework site, my answer is not correct.

I am getting a crazy answer of -179975.2.

Below is the image of my work. Any help would be GREATLY appreciated, as this assignment is due soon.

I apologies for the large image for those with small screens.

[PLAIN]http://img139.imageshack.us/img139/1324/68070772.jpg
 
Last edited by a moderator:
Physics news on Phys.org
Your region D is drawn incorrectly. The line intersects the curve at (-8, -1) and (0, 3). You have intersection points of (0, 3), which is mislabeled, and (16, 5). Your point at (0, 3) is below the x-axis, so should be labeled (0, -3).
 
Thank you. The only thing I had to change was the limit of 16 to -9 to 3 to -1 and got the answer correct with the same approach as above. You are correct about the fact that I drew the D region incorrectly... stupid mistake on my part.
 

Similar threads

  • · Replies 17 ·
Replies
17
Views
4K
Replies
2
Views
1K
Replies
10
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
18
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
12
Views
5K
Replies
4
Views
3K
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K