10=d^2-5d

Solution for 10=d^2-5d equation:

10=d^2-5d

We move all terms to the left:

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

We get rid of parentheses

-d^2+5d+10=0

We add all the numbers together, and all the variables

-1d^2+5d+10=0

a = -1; b = 5; c = +10;
Δ = b2-4ac
Δ = 52-4·(-1)·10
Δ = 65
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-\sqrt{65}}{2*-1}=\frac{-5-\sqrt{65}}{-2}
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+\sqrt{65}}{2*-1}=\frac{-5+\sqrt{65}}{-2}
$