x^2-0.8x=0.26

Solution for x^2-0.8x=0.26 equation:

x^2-0.8x=0.26

We move all terms to the left:

x^2-0.8x-(0.26)=0

We add all the numbers together, and all the variables

x^2-0.8x-0.26=0

a = 1; b = -0.8; c = -0.26;
Δ = b2-4ac
Δ = -0.82-4·1·(-0.26)
Δ = 1.68
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{-(-0.8)-\sqrt{1.68}}{2*1}=\frac{0.8-\sqrt{1.68}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.8)+\sqrt{1.68}}{2*1}=\frac{0.8+\sqrt{1.68}}{2}
$