Given the inequality:
$$3 x^{2} \geq 3$$
To solve this inequality, we must first solve the corresponding equation:
$$3 x^{2} = 3$$
Solve:
Move right part of the equation to
left part with negative sign.
The equation is transformed from
$$3 x^{2} = 3$$
to
$$3 x^{2} - 3 = 0$$
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
$$a = 3$$
$$b = 0$$
$$c = -3$$
, then
D = b^2 - 4 * a * c =
(0)^2 - 4 * (3) * (-3) = 36
Because D > 0, then the equation has two roots.
x1 = (-b + sqrt(D)) / (2*a)
x2 = (-b - sqrt(D)) / (2*a)
or
$$x_{1} = 1$$
$$x_{2} = -1$$
$$x_{1} = 1$$
$$x_{2} = -1$$
$$x_{1} = 1$$
$$x_{2} = -1$$
This roots
$$x_{2} = -1$$
$$x_{1} = 1$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} \leq x_{2}$$
For example, let's take the point
$$x_{0} = x_{2} - \frac{1}{10}$$
=
$$-1 + - \frac{1}{10}$$
=
$$- \frac{11}{10}$$
substitute to the expression
$$3 x^{2} \geq 3$$
$$3 \left(- \frac{11}{10}\right)^{2} \geq 3$$
363
--- >= 3
100
one of the solutions of our inequality is:
$$x \leq -1$$
_____ _____
\ /
-------•-------•-------
x2 x1
Other solutions will get with the changeover to the next point
etc.
The answer:
$$x \leq -1$$
$$x \geq 1$$