(d+2)(d+13)=0

Solution for (d+2)(d+13)=0 equation:

(d+2)(d+13)=0

We multiply parentheses ..

(+d^2+13d+2d+26)=0

We get rid of parentheses

d^2+13d+2d+26=0

We add all the numbers together, and all the variables

d^2+15d+26=0

a = 1; b = 15; c = +26;
Δ = b2-4ac
Δ = 152-4·1·26
Δ = 121
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{121}=11$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-11}{2*1}=\frac{-26}{2}
=-13
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+11}{2*1}=\frac{-4}{2}
=-2
$