x2+2x=1.25

Solution for x2+2x=1.25 equation:

x2+2x=1.25

We move all terms to the left:

x2+2x-(1.25)=0

We add all the numbers together, and all the variables

x^2+2x-1.25=0

a = 1; b = 2; c = -1.25;
Δ = b2-4ac
Δ = 22-4·1·(-1.25)
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-3}{2*1}=\frac{-5}{2}
=-2+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+3}{2*1}=\frac{1}{2}
=1/2
$