(x-0.3)(2x-0.5)=0

Solution for (x-0.3)(2x-0.5)=0 equation:

(x-0.3)(2x-0.5)=0

We multiply parentheses ..

(+2x^2-0.5x-0.6x+0.15)=0

We get rid of parentheses

2x^2-0.5x-0.6x+0.15=0

We add all the numbers together, and all the variables

2x^2-1.1x+0.15=0

a = 2; b = -1.1; c = +0.15;
Δ = b2-4ac
Δ = -1.12-4·2·0.15
Δ = 0.01
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{-(-1.1)-\sqrt{0.01}}{2*2}=\frac{1.1-\sqrt{0.01}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.1)+\sqrt{0.01}}{2*2}=\frac{1.1+\sqrt{0.01}}{4}
$