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2x+1/3-4x-x^2/12=x^2-4/9 equation

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Numerical solution:

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The solution

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                   2         
                  x     2   4
2*x + 1/3 - 4*x - -- = x  - -
                  12        9
$$- \frac{x^{2}}{12} + \left(- 4 x + \left(2 x + \frac{1}{3}\right)\right) = x^{2} - \frac{4}{9}$$
Detail solution
Move right part of the equation to
left part with negative sign.

The equation is transformed from
$$- \frac{x^{2}}{12} + \left(- 4 x + \left(2 x + \frac{1}{3}\right)\right) = x^{2} - \frac{4}{9}$$
to
$$\left(\frac{4}{9} - x^{2}\right) + \left(- \frac{x^{2}}{12} + \left(- 4 x + \left(2 x + \frac{1}{3}\right)\right)\right) = 0$$
Expand the expression in the equation
$$\left(\frac{4}{9} - x^{2}\right) + \left(- \frac{x^{2}}{12} + \left(- 4 x + \left(2 x + \frac{1}{3}\right)\right)\right) = 0$$
We get the quadratic equation
$$- \frac{13 x^{2}}{12} - 2 x + \frac{7}{9} = 0$$
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
$$a = - \frac{13}{12}$$
$$b = -2$$
$$c = \frac{7}{9}$$
, then
D = b^2 - 4 * a * c = 

(-2)^2 - 4 * (-13/12) * (7/9) = 199/27

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

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

or
$$x_{1} = - \frac{2 \sqrt{597}}{39} - \frac{12}{13}$$
$$x_{2} = - \frac{12}{13} + \frac{2 \sqrt{597}}{39}$$
Vieta's Theorem
rewrite the equation
$$- \frac{x^{2}}{12} + \left(- 4 x + \left(2 x + \frac{1}{3}\right)\right) = x^{2} - \frac{4}{9}$$
of
$$a x^{2} + b x + c = 0$$
as reduced quadratic equation
$$x^{2} + \frac{b x}{a} + \frac{c}{a} = 0$$
$$x^{2} + \frac{24 x}{13} - \frac{28}{39} = 0$$
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = \frac{24}{13}$$
$$q = \frac{c}{a}$$
$$q = - \frac{28}{39}$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = - \frac{24}{13}$$
$$x_{1} x_{2} = - \frac{28}{39}$$
The graph
Sum and product of roots [src]
sum
           _____              _____
  12   2*\/ 597      12   2*\/ 597 
- -- + --------- + - -- - ---------
  13       39        13       39   
$$\left(- \frac{2 \sqrt{597}}{39} - \frac{12}{13}\right) + \left(- \frac{12}{13} + \frac{2 \sqrt{597}}{39}\right)$$
=
-24 
----
 13 
$$- \frac{24}{13}$$
product
/           _____\ /           _____\
|  12   2*\/ 597 | |  12   2*\/ 597 |
|- -- + ---------|*|- -- - ---------|
\  13       39   / \  13       39   /
$$\left(- \frac{12}{13} + \frac{2 \sqrt{597}}{39}\right) \left(- \frac{2 \sqrt{597}}{39} - \frac{12}{13}\right)$$
=
-28 
----
 39 
$$- \frac{28}{39}$$
-28/39
Rapid solution [src]
                _____
       12   2*\/ 597 
x1 = - -- + ---------
       13       39   
$$x_{1} = - \frac{12}{13} + \frac{2 \sqrt{597}}{39}$$
                _____
       12   2*\/ 597 
x2 = - -- - ---------
       13       39   
$$x_{2} = - \frac{2 \sqrt{597}}{39} - \frac{12}{13}$$
x2 = -2*sqrt(597)/39 - 12/13
Numerical answer [src]
x1 = 0.329927356191858
x2 = -2.1760812023457
x2 = -2.1760812023457