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Simple integration problem

  • Thread starter PhyStan7
  • Start date
  • #1
18
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Hi all, im having a problem with an integration.


Solve the integration 3/(1+4x)^0.5 between x=0 and x=2. Basically find the area under a curve of the equation between x=0 and x=2.

I know the answer is 3 but cant get to it. I tried rewriting it as 3(1+4x)^-0.5 and solving bu got stupid answers like 15. and 21 to lots of dp. I cant find the mark scheme to the past paper i am doing anywhere on the internet so cant find a solution. Help would be much appreciared, thanks
 

Answers and Replies

  • #2
If you let u=1+4x, then the integral becomes 3/4*u^(-1/2)du for u from 1 to 9.
 
  • #3
16
0
If you let u=1+4x, then the integral becomes 3/4*u^(-1/2)du for u from 1 to 9.
3/(1+4x)^0.5 = 3 * (1+4x)^(-0,5)

Now you can use the common powers law with the exponent (-0,5).
Adding 1 to this gives (0,5).
 
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