-3b(b+10)=-9

Solution for -3b(b+10)=-9 equation:

-3b(b+10)=-9

We move all terms to the left:

-3b(b+10)-(-9)=0

We add all the numbers together, and all the variables

-3b(b+10)+9=0

We multiply parentheses

-3b^2-30b+9=0

a = -3; b = -30; c = +9;
Δ = b2-4ac
Δ = -302-4·(-3)·9
Δ = 1008
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1008}=\sqrt{144*7}=\sqrt{144}*\sqrt{7}=12\sqrt{7}$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-12\sqrt{7}}{2*-3}=\frac{30-12\sqrt{7}}{-6}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+12\sqrt{7}}{2*-3}=\frac{30+12\sqrt{7}}{-6}
$