(d+5)(d+5)=36

Solution for (d+5)(d+5)=36 equation:

(d+5)(d+5)=36

We move all terms to the left:

(d+5)(d+5)-(36)=0

We multiply parentheses ..

(+d^2+5d+5d+25)-36=0

We get rid of parentheses

d^2+5d+5d+25-36=0

We add all the numbers together, and all the variables

d^2+10d-11=0

a = 1; b = 10; c = -11;
Δ = b2-4ac
Δ = 102-4·1·(-11)
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(10)-12}{2*1}=\frac{-22}{2}
=-11
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(10)+12}{2*1}=\frac{2}{2}
=1
$