Area between curves y=((e^x)-(e^-x))/2 and y=2e^-x

In summary, the conversation is about solving for the area between two curves, y=((e^x)-(e^-x))/2 and y=2e^-x, for a given interval. The homework equations involve using the formula for the integral of ( u(x)-l(x) )dx, but the person is having trouble integrating the given equations. They have tried graphing and solving for the intersection point, but have been unable to get the correct answer. They are considering splitting the formula into smaller integrals, but are unsure if they can use the linearity subtraction rule.
  • #1
shft600
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0

Homework Statement



Area between curves y=((e^x)-(e^-x))/2 and y=2e^-x for -1 < x < 2

Homework Equations


I know the formula is the integral of ( u(x)-l(x) )dx, but I'm having a lot of trouble trying to integrate this.

integral from -1 to ln(5)/2: (((2e^-x)-((e^x)-(e^-x))/2))dx + int. ln(5)/2 to 2: (((e^x)-(e^-x))/2-2e^-x)dx

The Attempt at a Solution


I graphed everything and solved for x (intersection at x=ln(5)/2) but have been unable to get the right answer after that point. I tried splitting the formula into smaller integrals by linearity to simplify integration but consistently got the wrong answer for that.
Should I try to split it up again? Or am I missing a pretty easy integration in here?
 
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  • #2
well, I'm trying this question again so just thought i'd bump with a little question to get started.

since the first half of the area integral works out to be:

A = int: {2e-x-(ex-e-x)/2}dx

can I just separate it into:

A = int: 2e-xdx - int: (ex-e-x)/2dx

or is the fact that the two formulas are in brackets rule out the linearity subtraction rule?
 
  • #3
k got this one too, bury this thread as desired
 

1. What is the area between the two curves y=((e^x)-(e^-x))/2 and y=2e^-x?

The area between the two curves can be found by taking the definite integral of the larger curve (y=((e^x)-(e^-x))/2) minus the definite integral of the smaller curve (y=2e^-x) within the given bounds. Graphically, it represents the shaded region between the two curves.

2. How do I set up the integral to find the area between these two curves?

To set up the integral, you can use the formula: ∫(f(x) - g(x)) dx, where f(x) is the upper curve and g(x) is the lower curve. In this case, it would be ∫(((e^x)-(e^-x))/2 - 2e^-x) dx. You would then integrate this expression within the given bounds.

3. Can I use any method to solve for the area between two curves?

Yes, there are multiple methods to calculate the area between two curves, such as using the trapezoidal rule or Simpson's rule. However, using integration is the most common and reliable method.

4. What are the bounds for finding the area between these two curves?

The bounds for finding the area between the two curves are determined by the points of intersection between the two curves. These points can be found by setting the equations equal to each other and solving for x.

5. Is the area between two curves always positive?

No, the area between two curves can be positive or negative depending on the orientation of the curves. For example, if the upper curve is below the lower curve in certain regions, the resulting area would be negative.

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