# Thread: integral of dx/(a^2 + bx + x^2)^1.5

1. ## integral of dx/(a^2 + bx + x^2)^1.5

Hi
Can anybody help me with this one : integral of dx/(a^2 + bx + x^2)^1.5

Thanks

2. ## Re: integral of dx/(a^2 + bx + x^2)^1.5

Originally Posted by Roger44
Hi
Can anybody help me with this one : integral of dx/(a^2 + bx + x^2)^1.5
Have a look HERE.

3. ## Re: integral of dx/(a^2 + bx + x^2)^1.5

You would complete the square in the polynomial and then look for a trigonometric substitution, I think.

4. ## Re: integral of dx/(a^2 + bx + x^2)^1.5

Plato, the link you gave me was perfect. Two other sites I had tried before didn't find a solution. Many thanks

The formula I submitted gives the lumens/sq m on a point on the floor coming from a bulb fixed to the wall, and this integral will give me lumens/sq m on a point on the floor coming from a horizontal strip of light fixed to the wall.

5. ## Re: integral of dx/(a^2 + bx + x^2)^1.5

Hello again

Wolfram gives this solution for another integral but as you can see only if a>b. Or this is a real world situation where a will be rarely less than b. Any workaround?