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13*x^2-330*x-208=0 equation

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Numerical solution:

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The solution

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13*x  - 330*x - 208 = 0
$$\left(13 x^{2} - 330 x\right) - 208 = 0$$
Detail solution
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
$$a = 13$$
$$b = -330$$
$$c = -208$$
, then
D = b^2 - 4 * a * c = 

(-330)^2 - 4 * (13) * (-208) = 119716

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

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

or
$$x_{1} = 26$$
$$x_{2} = - \frac{8}{13}$$
Vieta's Theorem
rewrite the equation
$$\left(13 x^{2} - 330 x\right) - 208 = 0$$
of
$$a x^{2} + b x + c = 0$$
as reduced quadratic equation
$$x^{2} + \frac{b x}{a} + \frac{c}{a} = 0$$
$$x^{2} - \frac{330 x}{13} - 16 = 0$$
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = - \frac{330}{13}$$
$$q = \frac{c}{a}$$
$$q = -16$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = \frac{330}{13}$$
$$x_{1} x_{2} = -16$$
Sum and product of roots [src]
sum
26 - 8/13
$$- \frac{8}{13} + 26$$
=
330
---
 13
$$\frac{330}{13}$$
product
26*(-8)
-------
   13  
$$\frac{\left(-8\right) 26}{13}$$
=
-16
$$-16$$
-16
Rapid solution [src]
x1 = -8/13
$$x_{1} = - \frac{8}{13}$$
x2 = 26
$$x_{2} = 26$$
x2 = 26
Numerical answer [src]
x1 = -0.615384615384615
x2 = 26.0
x2 = 26.0