Let $f\left(x\right)=\left[2x^3-5\right],\left[.\right]$ denotes the greatest integer function. Then number of points in (1, 2) where the 

function is discontinuous, is

Since $\varphi \left(x\right)=2x^3-5$ is an increasing function on(1, 2) such that  $\varphi \left(1\right)=-3$ and $\varphi \left(2\right)=11.$

Clearly, between - 3 and 11 there are thirteen points where$f\left(x\right)=\left[2x^3-5\right]$ is discontinuous