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(5-4x)/(3x^2-x-4)<4 inequation

A inequation with variable

The solution

You have entered [src]
  5 - 4*x       
------------ < 4
   2            
3*x  - x - 4    
$$\frac{5 - 4 x}{\left(3 x^{2} - x\right) - 4} < 4$$
(5 - 4*x)/(3*x^2 - x - 4) < 4
Detail solution
Given the inequality:
$$\frac{5 - 4 x}{\left(3 x^{2} - x\right) - 4} < 4$$
To solve this inequality, we must first solve the corresponding equation:
$$\frac{5 - 4 x}{\left(3 x^{2} - x\right) - 4} = 4$$
Solve:
Given the equation:
$$\frac{5 - 4 x}{\left(3 x^{2} - x\right) - 4} = 4$$
Multiply the equation sides by the denominators:
-4 - x + 3*x^2
we get:
$$\frac{\left(5 - 4 x\right) \left(3 x^{2} - x - 4\right)}{\left(3 x^{2} - x\right) - 4} = 12 x^{2} - 4 x - 16$$
$$5 - 4 x = 12 x^{2} - 4 x - 16$$
Move right part of the equation to
left part with negative sign.

The equation is transformed from
$$5 - 4 x = 12 x^{2} - 4 x - 16$$
to
$$21 - 12 x^{2} = 0$$
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
$$a = -12$$
$$b = 0$$
$$c = 21$$
, then
D = b^2 - 4 * a * c = 

(0)^2 - 4 * (-12) * (21) = 1008

Because D > 0, then the equation has two roots.
x1 = (-b + sqrt(D)) / (2*a)

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

or
$$x_{1} = - \frac{\sqrt{7}}{2}$$
$$x_{2} = \frac{\sqrt{7}}{2}$$
$$x_{1} = - \frac{\sqrt{7}}{2}$$
$$x_{2} = \frac{\sqrt{7}}{2}$$
$$x_{1} = - \frac{\sqrt{7}}{2}$$
$$x_{2} = \frac{\sqrt{7}}{2}$$
This roots
$$x_{1} = - \frac{\sqrt{7}}{2}$$
$$x_{2} = \frac{\sqrt{7}}{2}$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} < x_{1}$$
For example, let's take the point
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$- \frac{\sqrt{7}}{2} - \frac{1}{10}$$
=
$$- \frac{\sqrt{7}}{2} - \frac{1}{10}$$
substitute to the expression
$$\frac{5 - 4 x}{\left(3 x^{2} - x\right) - 4} < 4$$
$$\frac{5 - 4 \left(- \frac{\sqrt{7}}{2} - \frac{1}{10}\right)}{-4 + \left(- (- \frac{\sqrt{7}}{2} - \frac{1}{10}) + 3 \left(- \frac{\sqrt{7}}{2} - \frac{1}{10}\right)^{2}\right)} < 4$$
          27       ___              
          -- + 2*\/ 7               
          5                         
--------------------------------    
                               2 < 4
         ___     /         ___\     
  39   \/ 7      |  1    \/ 7 |     
- -- + ----- + 3*|- -- - -----|     
  10     2       \  10     2  /     

one of the solutions of our inequality is:
$$x < - \frac{\sqrt{7}}{2}$$
 _____           _____          
      \         /
-------ο-------ο-------
       x1      x2

Other solutions will get with the changeover to the next point
etc.
The answer:
$$x < - \frac{\sqrt{7}}{2}$$
$$x > \frac{\sqrt{7}}{2}$$
Solving inequality on a graph
Rapid solution [src]
  /   /                ___ \     /              ___\                      \
  |   |             -\/ 7  |     |            \/ 7 |                      |
Or|And|-oo < x, x < -------|, And|-1 < x, x < -----|, And(4/3 < x, x < oo)|
  \   \                2   /     \              2  /                      /
$$\left(-\infty < x \wedge x < - \frac{\sqrt{7}}{2}\right) \vee \left(-1 < x \wedge x < \frac{\sqrt{7}}{2}\right) \vee \left(\frac{4}{3} < x \wedge x < \infty\right)$$
((4/3 < x)∧(x < oo))∨((-oo < x)∧(x < -sqrt(7)/2))∨((-1 < x)∧(x < sqrt(7)/2))
Rapid solution 2 [src]
         ___            ___             
      -\/ 7           \/ 7              
(-oo, -------) U (-1, -----) U (4/3, oo)
         2              2               
$$x\ in\ \left(-\infty, - \frac{\sqrt{7}}{2}\right) \cup \left(-1, \frac{\sqrt{7}}{2}\right) \cup \left(\frac{4}{3}, \infty\right)$$
x in Union(Interval.open(-oo, -sqrt(7)/2), Interval.open(-1, sqrt(7)/2), Interval.open(4/3, oo))