May 16th, 2019, 08:27 AM  #1 
Member Joined: Oct 2012 Posts: 78 Thanks: 0  without substituting
If f(x)=root(9x^2) find the integration of f(x) in the interval [0,3] without using trigonometric substituting.

May 16th, 2019, 09:19 AM  #2 
Global Moderator Joined: Dec 2006 Posts: 20,926 Thanks: 2205 
Hint: show on a simple graph an area corresponding to the value of the integral. You may assume that the area of a unit circle is $\pi$.

May 16th, 2019, 08:44 PM  #3 
Member Joined: Oct 2012 Posts: 78 Thanks: 0  Ok. Is there an algebraic method to solve rather than sketching?
Last edited by skipjack; May 17th, 2019 at 09:00 AM. 
May 17th, 2019, 09:10 AM  #4 
Global Moderator Joined: Dec 2006 Posts: 20,926 Thanks: 2205 
The answer involves $\pi$, which you wouldn't be able to obtain by a purely algebraic method.


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