2.6=x^2+2x+1

Solution for 2.6=x^2+2x+1 equation:

2.6=x^2+2x+1

We move all terms to the left:

2.6-(x^2+2x+1)=0

We get rid of parentheses

-x^2-2x-1+2.6=0

We add all the numbers together, and all the variables

-1x^2-2x+1.6=0

a = -1; b = -2; c = +1.6;
Δ = b2-4ac
Δ = -22-4·(-1)·1.6
Δ = 10.4
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)-\sqrt{10.4}}{2*-1}=\frac{2-\sqrt{10.4}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+\sqrt{10.4}}{2*-1}=\frac{2+\sqrt{10.4}}{-2}
$