![\displaystyle\lim_{n\to\infty}\sqrt[n]{\left|\left(\frac{5n+15}{2n-1}\right)^n\right|}=\lim_{n\to\infty}\frac{5n+15}{2n-1}=\dfrac52](https://tex.z-dn.net/?f=%5Cdisplaystyle%5Clim_%7Bn%5Cto%5Cinfty%7D%5Csqrt%5Bn%5D%7B%5Cleft%7C%5Cleft%28%5Cfrac%7B5n%2B15%7D%7B2n-1%7D%5Cright%29%5En%5Cright%7C%7D%3D%5Clim_%7Bn%5Cto%5Cinfty%7D%5Cfrac%7B5n%2B15%7D%7B2n-1%7D%3D%5Cdfrac52)
Since this limit exceeds 1, the series diverges.
Assuming you meant is

The answer would be :




Hope this helps !
Photon
However, your equation seems weird :o
3x _> 3.0 - 2.4
= 3x _> 3/5
= 1/5

is undefined where the denominator is zero. The domain is all values of x for which the function is defined.
The domain of f(x) is all real numbers except 13.