0=x^2+3x-378

Solution for 0=x^2+3x-378 equation:

0=x^2+3x-378

We move all terms to the left:

0-(x^2+3x-378)=0

We add all the numbers together, and all the variables

-(x^2+3x-378)=0

We get rid of parentheses

-x^2-3x+378=0

We add all the numbers together, and all the variables

-1x^2-3x+378=0

a = -1; b = -3; c = +378;
Δ = b2-4ac
Δ = -32-4·(-1)·378
Δ = 1521
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1521}=39$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-39}{2*-1}=\frac{-36}{-2}
=+18
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+39}{2*-1}=\frac{42}{-2}
=-21
$