x^2-39x+378=0

Solution for x^2-39x+378=0 equation:

x^2-39x+378=0

a = 1; b = -39; c = +378;
Δ = b2-4ac
Δ = -392-4·1·378
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-39)-3}{2*1}=\frac{36}{2}
=18
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-39)+3}{2*1}=\frac{42}{2}
=21
$