$\int\limits_0^1\frac{dx}{\sqrt{1+x}-\sqrt{x}}$ is equal to
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → $\frac{4\sqrt{2}}{3}$
Evaluate the integral:
$\int_{0}^{1} \frac{dx}{\sqrt{1+x}-\sqrt{x}}$
Rationalize the denominator:
$\frac{1}{\sqrt{1+x}-\sqrt{x}} \cdot \frac{\sqrt{1+x}+\sqrt{x}}{\sqrt{1+x}+\sqrt{x}} =\frac{\sqrt{1+x}+\sqrt{x}}{(1+x)-x} =\sqrt{1+x}+\sqrt{x}$
Thus the integral becomes:
$\int_{0}^{1} \left(\sqrt{1+x}+\sqrt{x}\right)\,dx$
$\int_{0}^{1}\sqrt{1+x}\,dx+\int_{0}^{1}\sqrt{x}\,dx$
Compute each:
$\int\sqrt{1+x}\,dx=\frac{2}{3}(1+x)^{3/2}$
$\int\sqrt{x}\,dx=\frac{2}{3}x^{3/2}$
$\frac{2}{3}(2\sqrt{2}-1)+\frac{2}{3} =\frac{2}{3}(2\sqrt{2}-1+1) =\frac{2}{3}(2\sqrt{2})$
$=\frac{4\sqrt{2}}{3}$
The value of the integral is $\frac{4\sqrt{2}}{3}$.