‹ Back to the paper
Solve the following.
Evaluate: ∫ tan⁻¹√x dx
Evaluate: $\int \tan^{-1}\sqrt{x} dx$
Answer
Answer
Integral: $\int \left(\tan^{-1}\sqrt{x}\right) dx$
Integrating by parts with $u = \tan^{-1}\sqrt{x}$, $dv = dx$:
$\int \tan^{-1}\sqrt{x}\,dx = x\tan^{-1}\sqrt{x} - \int x\cdot\frac{1}{1+x}\cdot\frac{1}{2\sqrt{x}}dx$
$= x\tan^{-1}\sqrt{x} - \frac{1}{2}\int \frac{\sqrt{x}}{1+x}dx$.
Put $\sqrt{x} = t$, $dx = 2t\,dt$: $\frac{1}{2}\int\frac{t\cdot 2t}{1+t^2}dt = \int\left(1 - \frac{1}{1+t^2}\right)dt = t - \tan^{-1}t$.
Hence $\int \tan^{-1}\sqrt{x}\,dx = x\tan^{-1}\sqrt{x} - \sqrt{x} + \tan^{-1}\sqrt{x} + C = (x+1)\tan^{-1}\sqrt{x} - \sqrt{x} + C$.
Final answer: $(x+1)\tan^{-1}\sqrt{x} - \sqrt{x}$