105=x^2+x

Solution for 105=x^2+x equation:

105=x^2+x

We move all terms to the left:

105-(x^2+x)=0

We get rid of parentheses

-x^2-x+105=0

We add all the numbers together, and all the variables

-1x^2-1x+105=0

a = -1; b = -1; c = +105;
Δ = b2-4ac
Δ = -12-4·(-1)·105
Δ = 421
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{-(-1)-\sqrt{421}}{2*-1}=\frac{1-\sqrt{421}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{421}}{2*-1}=\frac{1+\sqrt{421}}{-2}
$