Solve Integration Problem: Find Area Between f(x) & g(x)

  • Thread starter Thread starter stanners
  • Start date Start date
  • Tags Tags
    Integration
stanners
Messages
11
Reaction score
0
Sorry this is the first time using this forum.. so I'm not too good with writing out the equations

Homework Statement


Find the area of the region between the curves f(x) = 3x^2 and g(x) = sqrt(x/3) for 0 <= x <= 1.


Homework Equations





The Attempt at a Solution


So.. since g(x) is greater than f(x) from 0 to 1/3, and less from 1/3 to 1.

I set up the integrals

[int. from 0 to 1/3 of g(x) - int. from 0 to 1/3 of f(x)] + [int. from 1/3 to 1 of f(x) - int. from 1/3 to 1 of g(x)]

Is that set up correctly?

Next is where my problem is... :confused:
integral of 3x^2 is x^3, but how do I integrate sqrt(x/3) ?

I used the power rule and got [2(x/3)^3/2]/3, but that doesn't seem right, please help me out with this.

Thanks!
 
Physics news on Phys.org
Your method seems fine but your integration of the square root is slightly out. Try integrating the following and see why you are slightly out.

\frac{1}{\sqrt{3}}\times x^{\frac{1}{2}}
 
Last edited:
Yeah, just factor out the 1/sqrt[3] and treat the sqrt[x] on its own.
 
So would I end up with 1/sqrt(3) * int. (x^3/2) / (3/2) ?
 
stanners said:
So would I end up with 1/sqrt(3) * int. (x^3/2) / (3/2) ?

Yes, of course, but without the integral sign thingy. :)
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top