x2-2x=0.64

Solution for x2-2x=0.64 equation:

x2-2x=0.64

We move all terms to the left:

x2-2x-(0.64)=0

We add all the numbers together, and all the variables

x^2-2x-0.64=0

a = 1; b = -2; c = -0.64;
Δ = b2-4ac
Δ = -22-4·1·(-0.64)
Δ = 6.56
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{6.56}}{2*1}=\frac{2-\sqrt{6.56}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+\sqrt{6.56}}{2*1}=\frac{2+\sqrt{6.56}}{2}
$