Here is another problem that might be related to my last post. These dang sec and tan. Anyway, here goes...(adsbygoogle = window.adsbygoogle || []).push({});

[tex]\int\frac{x^3}\sqrt{{x^2+1}}\dx[/tex]

Oh man.. above is a feeble attempt to write with the LaTeX language. that was my first attempt and a terrible one at that. Haha.. Sorry about that. Anyway, to the question.

I am trying to integrate ∫(x^3)/((x^+1)^(1/2)) dx

To start, I let x = tan(θ) which lets dx = sec^2(θ) dθ

Plugging this back into the equation, we get ∫ (tan^3(θ)/((tan^2(θ)+1)^(1/2)) sex^2(θ) dθ.

Solving the algebra I come to a point that I do not know what to do next.

That is, ∫ tan^3(θ)sec(θ) dθ.

Can anyone offer any advice as to what the next step would be?

Thank you

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Another tan and sec integral issue

**Physics Forums | Science Articles, Homework Help, Discussion**