u^2-2u+.9=0

Solution for u^2-2u+.9=0 equation:

u^2-2u+.9=0

We add all the numbers together, and all the variables

u^2-2u+0.9=0

a = 1; b = -2; c = +0.9;
Δ = b2-4ac
Δ = -22-4·1·0.9
Δ = 0.4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-\sqrt{0.4}}{2*1}=\frac{2-\sqrt{0.4}}{2}
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+\sqrt{0.4}}{2*1}=\frac{2+\sqrt{0.4}}{2}
$