(x-1)(x-123)=0

Solution for (x-1)(x-123)=0 equation:

(x-1)(x-123)=0

We multiply parentheses ..

(+x^2-123x-1x+123)=0

We get rid of parentheses

x^2-123x-1x+123=0

We add all the numbers together, and all the variables

x^2-124x+123=0

a = 1; b = -124; c = +123;
Δ = b2-4ac
Δ = -1242-4·1·123
Δ = 14884
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{14884}=122$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-124)-122}{2*1}=\frac{2}{2}
=1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-124)+122}{2*1}=\frac{246}{2}
=123
$