3b(5b+2)=0

Solution for 3b(5b+2)=0 equation:

3b(5b+2)=0

We multiply parentheses

15b^2+6b=0

a = 15; b = 6; c = 0;
Δ = b2-4ac
Δ = 62-4·15·0
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-6}{2*15}=\frac{-12}{30}
=-2/5
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+6}{2*15}=\frac{0}{30}
=0
$