Saturday, 23 July 2016

integration - Check convergence of int10fracdx|sinx|1/2




Check convergence of integral: 10dx|sinx|1/2





My attempt



Dirichlet's test would't help there so I am going to use comparison test:



xsinx1x1sinx1|x|1|sinx|1|x|1/21|sinx|1/2
So




10dx|sinx|1/2101|x|1/2
But 101|x|1/2 converges so it doesn't help me.


Answer



Instead of using the upper bound sinxx, use the to lower bound sinx2xπ, which follows from sinx being concave on [0,π/2].


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