The slope of normal to the curve $x=\sqrt{t}$ and $y=t-\frac{1}{\sqrt{t}}$ at $t=4$ is ..........

If $f(x)=x+\frac{1}{x}, x \neq 0$, then local maximum and minimum values of function $f$ are respectively.......

The function $f(x)=x^3-3 x$ is ............

Using differentiation, approximate value of $f(x)=x^2-2 x+1$ at $x=2.99$ is ............