Mister Exam

x³-3x²-x+3>0 inequation

A inequation with variable

The solution

You have entered [src]
 3      2            
x  - 3*x  - x + 3 > 0
$$x^{3} - 3 x^{2} - x + 3 > 0$$
x^3 - 3*x^2 - x + 3 > 0
Detail solution
Given the inequality:
$$x^{3} - 3 x^{2} - x + 3 > 0$$
To solve this inequality, we must first solve the corresponding equation:
$$x^{3} - 3 x^{2} - x + 3 = 0$$
Solve:
$$x_{1} = 1$$
$$x_{2} = 3$$
$$x_{3} = -1$$
$$x_{1} = 1$$
$$x_{2} = 3$$
$$x_{3} = -1$$
This roots
$$x_{3} = -1$$
$$x_{1} = 1$$
$$x_{2} = 3$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} < x_{3}$$
For example, let's take the point
$$x_{0} = x_{3} - \frac{1}{10}$$
=
$$-1 - \frac{1}{10}$$
=
$$- \frac{11}{10}$$
substitute to the expression
$$x^{3} - 3 x^{2} - x + 3 > 0$$
$$- 3 \left(- \frac{11}{10}\right)^{2} + \left(- \frac{11}{10}\right)^{3} - - \frac{11}{10} + 3 > 0$$
-861     
----- > 0
 1000    

Then
$$x < -1$$
no execute
one of the solutions of our inequality is:
$$x > -1 \wedge x < 1$$
         _____           _____  
        /     \         /
-------ο-------ο-------ο-------
       x_3      x_1      x_2

Other solutions will get with the changeover to the next point
etc.
The answer:
$$x > -1 \wedge x < 1$$
$$x > 3$$
Solving inequality on a graph
Rapid solution [src]
Or(And(-1 < x, x < 1), And(3 < x, x < oo))
$$\left(-1 < x \wedge x < 1\right) \vee \left(3 < x \wedge x < \infty\right)$$
((-1 < x)∧(x < 1))∨((3 < x)∧(x < oo))
Rapid solution 2 [src]
(-1, 1) U (3, oo)
$$x\ in\ \left(-1, 1\right) \cup \left(3, \infty\right)$$
x in Union(Interval.open(-1, 1), Interval.open(3, oo))
The graph
x³-3x²-x+3>0 inequation