36=(b+9)(b+2)

Solution for 36=(b+9)(b+2) equation:

36=(b+9)(b+2)

We move all terms to the left:

36-((b+9)(b+2))=0

We multiply parentheses ..

-((+b^2+2b+9b+18))+36=0


We calculate terms in parentheses: -((+b^2+2b+9b+18)), so:

(+b^2+2b+9b+18)

We get rid of parentheses

b^2+2b+9b+18

We add all the numbers together, and all the variables

b^2+11b+18

Back to the equation:

-(b^2+11b+18)


We get rid of parentheses

-b^2-11b-18+36=0

We add all the numbers together, and all the variables

-1b^2-11b+18=0

a = -1; b = -11; c = +18;
Δ = b2-4ac
Δ = -112-4·(-1)·18
Δ = 193
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{-(-11)-\sqrt{193}}{2*-1}=\frac{11-\sqrt{193}}{-2}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-11)+\sqrt{193}}{2*-1}=\frac{11+\sqrt{193}}{-2}
$