Find the area between two curves - Help finding the limits of integration

In summary, the conversation is about finding the limits of integration for the curves f(x) = x^(2/3) and g(x) = x^(3/2). The conversation includes discussions about solving for x and using the fact that x^m * x^n = x^(m+n). Eventually, the limits of integration are determined to be 0 to 1, which is confirmed by evaluating the integral.
  • #1
Asphyxiated
264
0

Homework Statement



The curves are:

[tex] f(x)= x^{2/3} [/tex]

and

[tex] g(x)=x^{3/2} [/tex]

Homework Equations



I am assuming that:

[tex] x^{2/3} = x^{3/2} [/tex]

is going to give me the limits of integration but I don't know how to solve for x on this equation.

Could also put it this way:

[tex] \sqrt[3]{x^{2}} = \sqrt{x^{3}} [/tex]

but that doesn't help me much..

The Attempt at a Solution



no real attempt because I don't know what to do.
 
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  • #2
I don't know how to do with algebra but, here's a hint:

What two numbers can be raised to any power and still equal themselves?
 
  • #3
I would say, 0 and 1, right? because -1 will change signs if raised to an even power so that doesn't fit. If that's right what was the clue that that would be the answer?
 
  • #4
Your reasoning is correct. Just subtract the two terms so the difference is equal to 0 and factor out x2/3. Then find the roots.
 
  • #5
@VeeEight

I think you read the problem wrong because I can't factor out the x^(2/3) as the lines are x^3/2 and x^2/3, not the same, or else I could easily solve for x
 
  • #6
Asphyxiated said:
@VeeEight

I think you read the problem wrong because I can't factor out the x^(2/3) as the lines are x^3/2 and x^2/3, not the same, or else I could easily solve for x

Perhaps this would be useful.

xm*xn=xm+n
 
  • #7
If you have the equation x2/3 - x3/2 = 0, write this as x2/3(something - 1)
 
  • #8
@VeeEight

So with:

[tex] x^{2/3}(x^{5/6}-1) = 0 [/tex]

can it be solved for x like so:

[tex] \sqrt[3]{x^{2}} = 0 \rightarrow x = 0 [/tex]

and

[tex] \sqrt[6]{x^{5}}-1 = 0 [/tex]

[tex] \sqrt[6]{x^{5}}=1 \rightarrow x =1 [/tex]

so the limits will be 0 to 1? (I know those are the right limits because when the integral is evaluated from 0 to 1 the answer checks out in the back of the book).
 
  • #9
Yes, that is the correct approach.
 

1. How do I find the area between two curves?

To find the area between two curves, you will need to set up an integral using the formula A = ∫(upper curve - lower curve) dx. This means taking the integral of the difference between the two curves with respect to x. The limits of integration will be the x-values where the two curves intersect.

2. How do I determine the limits of integration?

The limits of integration can be determined by finding the x-values where the two curves intersect. This can be done by setting the two equations equal to each other and solving for x. These x-values will be the lower and upper limits of integration.

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

There are various methods that can be used to find the area between two curves, such as the trapezoidal rule, Simpson's rule, or the method of disks or washers. However, the most common and straightforward method is to set up an integral using the formula mentioned in the first question.

4. What should I do if the two curves do not intersect?

If the two curves do not intersect, then there is no enclosed area between them. In this case, you can either find the area between the curves on separate intervals or you can adjust the limits of integration to enclose the region between the curves.

5. Can I find the area between two curves if one of the curves is below the x-axis?

Yes, you can still find the area between two curves if one of the curves is below the x-axis. In this case, the integral will give a negative value, which represents the area below the x-axis. To find the total area between the curves, you will need to take the absolute value of the integral.

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