-0.75d2+0.9d+1.5=0

Solution for -0.75d2+0.9d+1.5=0 equation:

-0.75d^2+0.9d+1.5=0

a = -0.75; b = 0.9; c = +1.5;
Δ = b2-4ac
Δ = 0.92-4·(-0.75)·1.5
Δ = 5.31
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{-(0.9)-\sqrt{5.31}}{2*-0.75}=\frac{-0.9-\sqrt{5.31}}{-1.5}
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.9)+\sqrt{5.31}}{2*-0.75}=\frac{-0.9+\sqrt{5.31}}{-1.5}
$