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

Solution for (x+0.9)(x-0.9)=0 equation:

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

We use the square of the difference formula

x^2-0.81=0

a = 1; b = 0; c = -0.81;
Δ = b2-4ac
Δ = 02-4·1·(-0.81)
Δ = 3.24
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{-(0)-\sqrt{3.24}}{2*1}=\frac{0-\sqrt{3.24}}{2}
=-\frac{\sqrt{}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{3.24}}{2*1}=\frac{0+\sqrt{3.24}}{2}
=\frac{\sqrt{}}{2}
$