Do you want to know the value of the function, when x= -1?

If so, then,

g\left(-1\right)\ =\ 2\ \times\left(-1\right)^2-1\ -\ 4\ =\ 2\ -\ 1\ -\ 4\ =\ -3

So the value of g(x) is -3 when x = -1.

I found an answer from math.stackexchange.com

Why is the domain of $**f**(**x**)=\frac{2x^2}{**x**^**4**+**1**}$ all real numbers? It ...

The domain of a function **f** is all values **x** such that **f**(**x**) is defined. In this context, "all values **x**" means "all real numbers **x**" and "is defined" means "is ...

For more information, see Why is the domain of $**f**(**x**)=\frac{2x^2}{**x**^**4**+**1**}$ all real numbers? It ...

I found an answer from web.stanford.edu

**4**. Convex optimization problems

3 − 3x, p⋆. = −∞, local optimum at **x** = **1**. Convex optimization problems. **4**–3 ... the constraints fi(**x**) ≤ 0, hi(**x)=**0 are the explicit constraints.

For more information, see **4**. Convex optimization problems