20<-4*x^2 inequation

Given the inequality:
$$20 < - 4 x^{2}$$
To solve this inequality, we must first solve the corresponding equation:
$$20 = - 4 x^{2}$$
Solve:
Move right part of the equation to
left part with negative sign.

The equation is transformed from
$$20 = - 4 x^{2}$$
to
$$4 x^{2} + 20 = 0$$
This equation is of the form

a*x^2 + b*x + c = 0

A quadratic equation can be solved
using the discriminant.
The roots of the quadratic equation:
$$x_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$x_{2} = \frac{- \sqrt{D} - b}{2 a}$$
where D = b^2 - 4*a*c - it is the discriminant.
Because
$$a = 4$$
$$b = 0$$
$$c = 20$$
, then

D = b^2 - 4 * a * c = 

(0)^2 - 4 * (4) * (20) = -320

Because D<0, then the equation
has no real roots,
but complex roots is exists.

x1 = (-b + sqrt(D)) / (2*a)

x2 = (-b - sqrt(D)) / (2*a)

or
$$x_{1} = \sqrt{5} i$$
$$x_{2} = - \sqrt{5} i$$
$$x_{1} = \sqrt{5} i$$
$$x_{2} = - \sqrt{5} i$$
Exclude the complex solutions:
This equation has no roots,
this inequality is executed for any x value or has no solutions
check it
subtitute random point x, for example

x0 = 0

$$20 < - 4 \cdot 0^{2}$$

20 < 0

but

20 > 0

so the inequality has no solutions