b^2+12b+3b=0

Solution for b^2+12b+3b=0 equation:

b^2+12b+3b=0

We add all the numbers together, and all the variables

b^2+15b=0

a = 1; b = 15; c = 0;
Δ = b2-4ac
Δ = 152-4·1·0
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-15}{2*1}=\frac{-30}{2}
=-15
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+15}{2*1}=\frac{0}{2}
=0
$