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x^2+999x−1000=0. equation

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Numerical solution:

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The solution

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x  + 999*x - 1000 = 0
$$\left(x^{2} + 999 x\right) - 1000 = 0$$
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
$$a = 1$$
$$b = 999$$
$$c = -1000$$
, then
D = b^2 - 4 * a * c = 

(999)^2 - 4 * (1) * (-1000) = 1002001

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

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

or
$$x_{1} = 1$$
$$x_{2} = -1000$$
Vieta's Theorem
it is reduced quadratic equation
$$p x + q + x^{2} = 0$$
where
$$p = \frac{b}{a}$$
$$p = 999$$
$$q = \frac{c}{a}$$
$$q = -1000$$
Vieta Formulas
$$x_{1} + x_{2} = - p$$
$$x_{1} x_{2} = q$$
$$x_{1} + x_{2} = -999$$
$$x_{1} x_{2} = -1000$$
Rapid solution [src]
x1 = -1000
$$x_{1} = -1000$$
x2 = 1
$$x_{2} = 1$$
x2 = 1
Sum and product of roots [src]
sum
-1000 + 1
$$-1000 + 1$$
=
-999
$$-999$$
product
-1000
$$-1000$$
=
-1000
$$-1000$$
-1000
Numerical answer [src]
x1 = 1.0
x2 = -1000.0
x2 = -1000.0