(1.2-x)(3.8-x)=0

Solution for (1.2-x)(3.8-x)=0 equation:

(1.2-x)(3.8-x)=0

We add all the numbers together, and all the variables

(-1x+1.2)(-1x+3.8)=0

We multiply parentheses ..

(+x^2-3.8x-1.2x+4.56)=0

We get rid of parentheses

x^2-3.8x-1.2x+4.56=0

We add all the numbers together, and all the variables

x^2-5x+4.56=0

a = 1; b = -5; c = +4.56;
Δ = b2-4ac
Δ = -52-4·1·4.56
Δ = 6.76
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{-(-5)-\sqrt{6.76}}{2*1}=\frac{5-\sqrt{6.76}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+\sqrt{6.76}}{2*1}=\frac{5+\sqrt{6.76}}{2}
$