Which of the following is (are) TRUE?

Let  $f:[-1,2]\to R$ be given by  $f\left(x\right)=2x^2+x+\left[x^2\right]-\left[x\right]$, where  $\left[t\right]$ is greatest 
integer function  $\le t$. The no. Of points where  $f\left(x\right)$ is not continuous is ‘4’ 

) If the function  $f\left(x\right)=\frac{\sin 3x+\alpha \sin x-\beta \cos 3x}{x^3},x\in ℝ-\left\{0\right\}$ is continuous at  $x=0$ then  $f\left(0\right)$  is equal to ‘- 4’

Let  $a>0$, be a root of the equation  $2x^2+x-2=0$. If  $\underset{x\to \frac{1}{a}}{Lt}\frac{16(1-\cos (2+x-2x^2))}{{(1-ax)}^2}=\alpha +\beta \sqrt{17}$   where  $\alpha ,\beta \in z$, then  $\alpha -\beta =136$

Let  $f\left(x\right)=x^5+2x^3+3x+1,x\in ℝ$  and  $g\left(x\right)$ be a function such that $g\left(f\left(x\right)\right)=xforallx\in ℝ$,  then  $\frac{g^{\text{'}}\left(7\right)}{g\left(7\right)}=\frac{1}{14}$ (Here  $g\text{'}\left(x\right)$ means first derivate of  $g\left(x\right)w.r.tx$)