(x+0.9)(x+0.9)=4

Solution for (x+0.9)(x+0.9)=4 equation:

(x+0.9)(x+0.9)=4

We move all terms to the left:

(x+0.9)(x+0.9)-(4)=0

We multiply parentheses ..

(+x^2+0.9x+0.9x+0.81)-4=0

We get rid of parentheses

x^2+0.9x+0.9x+0.81-4=0

We add all the numbers together, and all the variables

x^2+1.8x-3.19=0

a = 1; b = 1.8; c = -3.19;
Δ = b2-4ac
Δ = 1.82-4·1·(-3.19)
Δ = 16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16}=4$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1.8)-4}{2*1}=\frac{-5.8}{2}
=-2+1/1.1111111111111
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.8)+4}{2*1}=\frac{2.2}{2}
=1+0.2/2
$