Get the area between two curvess

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Homework Help Overview

The discussion revolves around finding the area between two curves defined by the functions f(x) = sqrt(x+3) and g(x) = (x+3)/2. The original poster attempts to determine the area by calculating the definite integral of the difference between these functions over the interval defined by their intersection points.

Discussion Character

  • Mathematical reasoning, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants discuss the process of finding intersection points and setting up the integral. There are questions about the correctness of the integration steps and the resulting expression for the area.

Discussion Status

Some participants have offered guidance on potential errors in the integration process. There is acknowledgment of a mistake in the original poster's anti-derivative choice, and suggestions to re-evaluate the integration steps have been made. The discussion is ongoing with participants providing clarifications.

Contextual Notes

There is a noted discrepancy between the original poster's calculated area and the answer provided in the textbook, prompting further examination of the integration process.

madinsane
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Okay, so here are the two functions, f(x)= sqrt(x+3) and g(x) = (x+3)/2
my first step was to get the intersection points and it came out to be x=1 or -3
Then I drew a graph and that told me that the function sqrt(x+3) is always above the other function on the entire interval. So then I did integral f(x)-g(x) dx with upper and lower limits 1 and -3 and the integral gave me (using u substitution as well) 2/3(x+3)^3/2 - 1/4 x^2 +3/2x and then I put in the x values and got 13.3.

Okay so the problem is that the answer in the book is 4/3 and I have no idea where I have gone wrong. Can anyone put me on the right track and tell me where I went wrong
 
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I believe the problem is in the integral. That x term looks wrong, I suggest you integrate again and see where you went wrong, because yours is different than my solution and my solution gets the right answer.

Just to be a bit more clear, your actual integral is correct, but you made an error integrating.

edit:

Misread something, but yeah what arildno says works :).
 
Last edited:
Your flaw lies in your lack of parentheses in your integrated -g, you should have -(1/4x^2+3/2x) as your choice of anti-derivative, rather than what you wrote.
 
Thank you. I realize my error now :)
 

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