x^2-2.55x+0.42=0

Solution for x^2-2.55x+0.42=0 equation:

x^2-2.55x+0.42=0

a = 1; b = -2.55; c = +0.42;
Δ = b2-4ac
Δ = -2.552-4·1·0.42
Δ = 4.8225
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{-(-2.55)-\sqrt{4.8225}}{2*1}=\frac{2.55-\sqrt{4.8225}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2.55)+\sqrt{4.8225}}{2*1}=\frac{2.55+\sqrt{4.8225}}{2}
$