12,655=x2+15x+55

Solution for 12,655=x2+15x+55 equation:

12.655=x2+15x+55

We move all terms to the left:

12.655-(x2+15x+55)=0

We add all the numbers together, and all the variables

-(+x^2+15x+55)+12.655=0

We get rid of parentheses

-x^2-15x-55+12.655=0

We add all the numbers together, and all the variables

-1x^2-15x-42.345=0

a = -1; b = -15; c = -42.345;
Δ = b2-4ac
Δ = -152-4·(-1)·(-42.345)
Δ = 55.62
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-\sqrt{55.62}}{2*-1}=\frac{15-\sqrt{55.62}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+\sqrt{55.62}}{2*-1}=\frac{15+\sqrt{55.62}}{-2}
$