(3.2-x)(3.6+x)=0

Solution for (3.2-x)(3.6+x)=0 equation:

(3.2-x)(3.6+x)=0

We add all the numbers together, and all the variables

(-1x+3.2)(x+3.6)=0

We multiply parentheses ..

(-1x^2-3.6x+3.2x+11.52)=0

We get rid of parentheses

-1x^2-3.6x+3.2x+11.52=0

We add all the numbers together, and all the variables

-1x^2-0.4x+11.52=0

a = -1; b = -0.4; c = +11.52;
Δ = b2-4ac
Δ = -0.42-4·(-1)·11.52
Δ = 46.24
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{-(-0.4)-\sqrt{46.24}}{2*-1}=\frac{0.4-\sqrt{46.24}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.4)+\sqrt{46.24}}{2*-1}=\frac{0.4+\sqrt{46.24}}{-2}
$