I am doing a problem with PDF's and this integral is a roadblock.
I have $f(x)=\dfrac{200}{(x+10)^3}$ where $x>0$ and have solved that $\mathbb{E}(X)=10$.
I am working on finding $\mathbb{E}(X^2)$ and so far have $\mathbb{E}(X^2)=\displaystyle \int_0^\infty \frac{200x^2}{(x+10)^3}$.
How do I go about showing that $\mathbb{E}(X^2)$ diverges? I tried substitution but it doesn't seem to work