x^2+28x+187=391

Solution for x^2+28x+187=391 equation:

x^2+28x+187=391

We move all terms to the left:

x^2+28x+187-(391)=0

We add all the numbers together, and all the variables

x^2+28x-204=0

a = 1; b = 28; c = -204;
Δ = b2-4ac
Δ = 282-4·1·(-204)
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-40}{2*1}=\frac{-68}{2}
=-34
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+40}{2*1}=\frac{12}{2}
=6
$