x(0.2x-1)=13.2

Solution for x(0.2x-1)=13.2 equation:

x(0.2x-1)=13.2

We move all terms to the left:

x(0.2x-1)-(13.2)=0

We add all the numbers together, and all the variables

x(0.2x-1)-13.2=0

We multiply parentheses

0x^2-1x-13.2=0

We add all the numbers together, and all the variables

x^2-1x-13.2=0

a = 1; b = -1; c = -13.2;
Δ = b2-4ac
Δ = -12-4·1·(-13.2)
Δ = 53.8
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{-(-1)-\sqrt{53.8}}{2*1}=\frac{1-\sqrt{53.8}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{53.8}}{2*1}=\frac{1+\sqrt{53.8}}{2}
$