Saturday, 26 August 2017

Does the integral $intlimits_0^{infty}frac{sin^{2}x}{x^{2}ln(1+sqrt x)} dx$ converge?



Does the integral




$$\int\limits_0^\infty \frac{\sin^{2}x}{x^{2}\ln(1+\sqrt x)} dx$$



converge?



It's easy to check that $\int\limits_1^{\infty}\frac{\sin^{2}x}{x^{2}\ln(1+\sqrt x)} dx$ does converge, but I couldn't find the right method for either proving or disproving that $\int\limits_0^1 \frac{\sin^{2}x}{x^{2}\ln(1+\sqrt x)} dx$ converges.


Answer



We might check some equivalent for $x\mapsto \frac{\sin^2(x)}{x^2 \ln(1+\sqrt{x})}$ near zero.



hint: $$ \ln(1+x) = x + o(x)$$


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