(a-0.3)(a+0.6)=0

Solution for (a-0.3)(a+0.6)=0 equation:

(a-0.3)(a+0.6)=0

We multiply parentheses ..

(+a^2+0.6a-0.3a-0.18)=0

We get rid of parentheses

a^2+0.6a-0.3a-0.18=0

We add all the numbers together, and all the variables

a^2+0.3a-0.18=0

a = 1; b = 0.3; c = -0.18;
Δ = b2-4ac
Δ = 0.32-4·1·(-0.18)
Δ = 0.81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0.3)-\sqrt{0.81}}{2*1}=\frac{-0.3-\sqrt{0.81}}{2}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.3)+\sqrt{0.81}}{2*1}=\frac{-0.3+\sqrt{0.81}}{2}
$