(a+12)(a+1)=0

Solution for (a+12)(a+1)=0 equation:

(a+12)(a+1)=0

We multiply parentheses ..

(+a^2+a+12a+12)=0

We get rid of parentheses

a^2+a+12a+12=0

We add all the numbers together, and all the variables

a^2+13a+12=0

a = 1; b = 13; c = +12;
Δ = b2-4ac
Δ = 132-4·1·12
Δ = 121
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{121}=11$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(13)-11}{2*1}=\frac{-24}{2}
=-12
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(13)+11}{2*1}=\frac{-2}{2}
=-1
$