x2-2x=140

Solution for x2-2x=140 equation:

x2-2x=140

We move all terms to the left:

x2-2x-(140)=0

We add all the numbers together, and all the variables

x^2-2x-140=0

a = 1; b = -2; c = -140;
Δ = b2-4ac
Δ = -22-4·1·(-140)
Δ = 564
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{564}=\sqrt{4*141}=\sqrt{4}*\sqrt{141}=2\sqrt{141}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-2\sqrt{141}}{2*1}=\frac{2-2\sqrt{141}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+2\sqrt{141}}{2*1}=\frac{2+2\sqrt{141}}{2}
$