126=x^2-0.5x

Solution for 126=x^2-0.5x equation:

126=x^2-0.5x

We move all terms to the left:

126-(x^2-0.5x)=0

We get rid of parentheses

-x^2+0.5x+126=0

We add all the numbers together, and all the variables

-1x^2+0.5x+126=0

a = -1; b = 0.5; c = +126;
Δ = b2-4ac
Δ = 0.52-4·(-1)·126
Δ = 504.25
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{-(0.5)-\sqrt{504.25}}{2*-1}=\frac{-0.5-\sqrt{504.25}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.5)+\sqrt{504.25}}{2*-1}=\frac{-0.5+\sqrt{504.25}}{-2}
$