9d+9=d^2+d*2

Solution for 9d+9=d^2+d*2 equation:

9d+9=d^2+d*2

We move all terms to the left:

9d+9-(d^2+d*2)=0

We get rid of parentheses

-d^2+9d-d*2+9=0

We add all the numbers together, and all the variables

-1d^2+9d-d*2+9=0

Wy multiply elements

-1d^2+9d-2d+9=0

We add all the numbers together, and all the variables

-1d^2+7d+9=0

a = -1; b = 7; c = +9;
Δ = b2-4ac
Δ = 72-4·(-1)·9
Δ = 85
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{-(7)-\sqrt{85}}{2*-1}=\frac{-7-\sqrt{85}}{-2}
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+\sqrt{85}}{2*-1}=\frac{-7+\sqrt{85}}{-2}
$