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+x+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}
$