-5d2-12d+4=0

Solution for -5d2-12d+4=0 equation:

-5d^2-12d+4=0

a = -5; b = -12; c = +4;
Δ = b2-4ac
Δ = -122-4·(-5)·4
Δ = 224
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{224}=\sqrt{16*14}=\sqrt{16}*\sqrt{14}=4\sqrt{14}$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-4\sqrt{14}}{2*-5}=\frac{12-4\sqrt{14}}{-10}
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+4\sqrt{14}}{2*-5}=\frac{12+4\sqrt{14}}{-10}
$