How do I correctly find the area bounded by x=-3, y=-x^2-2x, and y=x^2-4?

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Homework Help Overview

The problem involves finding the area bounded by the vertical line x=-3 and the curves y=-x^2-2x and y=x^2-4. Participants are exploring the setup and calculations related to this area.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the bounds of integration and the functions involved, questioning whether the upper bound or the designation of the top curve is correct. There are attempts to compute the area, but results yield negative values, prompting further inquiry into the setup.

Discussion Status

The discussion is ongoing, with participants sharing their calculations and expressing confusion over the negative area result. Some guidance is offered regarding careful treatment of signs in the area calculation, and there is an acknowledgment of potential issues with the upper bound or curve designation.

Contextual Notes

Participants mention that the professor provided a specific setup for the problem, which is causing some uncertainty in their attempts to solve it. There is also a reference to the need to consider areas below the x-axis in their calculations.

Danny222444
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Homework Statement


FInd the area bounded by x=-3, y=-x^2-2x, and y=x^2-4. (Hint: Graph the picture)

2. The attempt at a solution
My professor did set up the problem in class, but its throwing me off. He set it up as the lower bound -3 to 2, with the function (2x^2+2x-4)dx. I tried solving this but I keep getting a negative number. Any idea on what I am doing wrong?
 
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Please give some details of your attempt at a solution.
 
Ok, I end up with Area=2(-2^3/3)-2^2-4(-2)-(2(-3^3/3)+(-3)^2-4(-3) and I end with -5/3. I know the area cannot be negative. I have a feeling the upper bound is wrong or -x^2-2x should be the top curve. But my professor set it up exactly like this, and I just can't seem to solve it.
 
Danny222444 said:
Ok, I end up with Area=2(-2^3/3)-2^2-4(-2)-(2(-3^3/3)+(-3)^2-4(-3) and I end with -5/3. I know the area cannot be negative. I have a feeling the upper bound is wrong or -x^2-2x should be the top curve. But my professor set it up exactly like this, and I just can't seem to solve it.
First, be careful when you write the equation: I guess you mean (-2)^3, not -2^3, etc.

Second, there is a problem with the signs in that equation for the area. How are you treating the part of the area that is below y = 0?
 

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