s^2+5.5s+2.5=0

Solution for s^2+5.5s+2.5=0 equation:

s^2+5.5s+2.5=0

a = 1; b = 5.5; c = +2.5;
Δ = b2-4ac
Δ = 5.52-4·1·2.5
Δ = 20.25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5.5)-\sqrt{20.25}}{2*1}=\frac{-5.5-\sqrt{20.25}}{2}
$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5.5)+\sqrt{20.25}}{2*1}=\frac{-5.5+\sqrt{20.25}}{2}
$