13*x^2-330*x-208=0 equation
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The solution
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]
$$- \frac{8}{13} + 26$$
$$\frac{330}{13}$$
$$\frac{\left(-8\right) 26}{13}$$
$$-16$$
$$x_{1} = - \frac{8}{13}$$
$$x_{2} = 26$$