X^2+3.5x+2.5=0

Solution for X^2+3.5x+2.5=0 equation:

X^2+3.5X+2.5=0

a = 1; b = 3.5; c = +2.5;
Δ = b2-4ac
Δ = 3.52-4·1·2.5
Δ = 2.25
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{-(3.5)-\sqrt{2.25}}{2*1}=\frac{-3.5-\sqrt{2.25}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3.5)+\sqrt{2.25}}{2*1}=\frac{-3.5+\sqrt{2.25}}{2}
$