0=d^2-4d-5

Solution for 0=d^2-4d-5 equation:

0=d^2-4d-5

We move all terms to the left:

0-(d^2-4d-5)=0

We add all the numbers together, and all the variables

-(d^2-4d-5)=0

We get rid of parentheses

-d^2+4d+5=0

We add all the numbers together, and all the variables

-1d^2+4d+5=0

a = -1; b = 4; c = +5;
Δ = b2-4ac
Δ = 42-4·(-1)·5
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-6}{2*-1}=\frac{-10}{-2}
=+5
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+6}{2*-1}=\frac{2}{-2}
=-1
$