0=x^2-2x-25.5

Solution for 0=x^2-2x-25.5 equation:

0=x^2-2x-25.5

We move all terms to the left:

0-(x^2-2x-25.5)=0

We add all the numbers together, and all the variables

-(x^2-2x-25.5)=0

We get rid of parentheses

-x^2+2x+25.5=0

We add all the numbers together, and all the variables

-1x^2+2x+25.5=0

a = -1; b = 2; c = +25.5;
Δ = b2-4ac
Δ = 22-4·(-1)·25.5
Δ = 106
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{-(2)-\sqrt{106}}{2*-1}=\frac{-2-\sqrt{106}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+\sqrt{106}}{2*-1}=\frac{-2+\sqrt{106}}{-2}
$