3=-0.5d^2+2d+3

Solution for 3=-0.5d^2+2d+3 equation:

3=-0.5d^2+2d+3

We move all terms to the left:

3-(-0.5d^2+2d+3)=0

We get rid of parentheses

0.5d^2-2d-3+3=0

We add all the numbers together, and all the variables

0.5d^2-2d=0

a = 0.5; b = -2; c = 0;
Δ = b2-4ac
Δ = -22-4·0.5·0
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-2}{2*0.5}=\frac{0}{1}
=0
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+2}{2*0.5}=\frac{4}{1}
=4
$