b2-9b=12=-2

Solution for b2-9b=12=-2 equation:

b2-9b=12=-2

We move all terms to the left:

b2-9b-(12)=0

We add all the numbers together, and all the variables

b^2-9b-12=0

a = 1; b = -9; c = -12;
Δ = b2-4ac
Δ = -92-4·1·(-12)
Δ = 129
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-\sqrt{129}}{2*1}=\frac{9-\sqrt{129}}{2}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+\sqrt{129}}{2*1}=\frac{9+\sqrt{129}}{2}
$