X2-2000x+21879=0

Solution for X2-2000x+21879=0 equation:

X2-2000X+21879=0

We add all the numbers together, and all the variables

X^2-2000X+21879=0

a = 1; b = -2000; c = +21879;
Δ = b2-4ac
Δ = -20002-4·1·21879
Δ = 3912484
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3912484}=1978$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2000)-1978}{2*1}=\frac{22}{2}
=11
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2000)+1978}{2*1}=\frac{3978}{2}
=1989
$