x^2+2,5x+2,5x+6,25=9

Solution for x^2+2,5x+2,5x+6,25=9 equation:

x^2+2.5x+2.5x+6.25=9

We move all terms to the left:

x^2+2.5x+2.5x+6.25-(9)=0

We add all the numbers together, and all the variables

x^2+5x-2.75=0

a = 1; b = 5; c = -2.75;
Δ = b2-4ac
Δ = 52-4·1·(-2.75)
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-6}{2*1}=\frac{-11}{2}
=-5+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+6}{2*1}=\frac{1}{2}
=1/2
$