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x^2-5*x+7=0

x^2-5*x+7=0 equation

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Numerical solution:

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The solution

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 2              
x  - 5*x + 7 = 0
$$\left(x^{2} - 5 x\right) + 7 = 0$$
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
$$a = 1$$
$$b = -5$$
$$c = 7$$
, then
D = b^2 - 4 * a * c = 

(-5)^2 - 4 * (1) * (7) = -3

Because D<0, then the equation
has no real roots,
but complex roots is exists.
x1 = (-b + sqrt(D)) / (2*a)

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

or
$$x_{1} = \frac{5}{2} + \frac{\sqrt{3} i}{2}$$
$$x_{2} = \frac{5}{2} - \frac{\sqrt{3} i}{2}$$
Vieta's Theorem
it is reduced quadratic equation
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = -5$$
$$q = \frac{c}{a}$$
$$q = 7$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = 5$$
$$x_{1} x_{2} = 7$$
The graph
Rapid solution [src]
             ___
     5   I*\/ 3 
x1 = - - -------
     2      2   
$$x_{1} = \frac{5}{2} - \frac{\sqrt{3} i}{2}$$
             ___
     5   I*\/ 3 
x2 = - + -------
     2      2   
$$x_{2} = \frac{5}{2} + \frac{\sqrt{3} i}{2}$$
x2 = 5/2 + sqrt(3)*i/2
Sum and product of roots [src]
sum
        ___           ___
5   I*\/ 3    5   I*\/ 3 
- - ------- + - + -------
2      2      2      2   
$$\left(\frac{5}{2} - \frac{\sqrt{3} i}{2}\right) + \left(\frac{5}{2} + \frac{\sqrt{3} i}{2}\right)$$
=
5
$$5$$
product
/        ___\ /        ___\
|5   I*\/ 3 | |5   I*\/ 3 |
|- - -------|*|- + -------|
\2      2   / \2      2   /
$$\left(\frac{5}{2} - \frac{\sqrt{3} i}{2}\right) \left(\frac{5}{2} + \frac{\sqrt{3} i}{2}\right)$$
=
7
$$7$$
7
Numerical answer [src]
x1 = 2.5 - 0.866025403784439*i
x2 = 2.5 + 0.866025403784439*i
x2 = 2.5 + 0.866025403784439*i
The graph
x^2-5*x+7=0 equation