(5+4d)(-6+4d)=0

Solution for (5+4d)(-6+4d)=0 equation:

(5+4d)(-6+4d)=0

We add all the numbers together, and all the variables

(4d+5)(4d-6)=0

We multiply parentheses ..

(+16d^2-24d+20d-30)=0

We get rid of parentheses

16d^2-24d+20d-30=0

We add all the numbers together, and all the variables

16d^2-4d-30=0

a = 16; b = -4; c = -30;
Δ = b2-4ac
Δ = -42-4·16·(-30)
Δ = 1936
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1936}=44$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-44}{2*16}=\frac{-40}{32}
=-1+1/4
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+44}{2*16}=\frac{48}{32}
=1+1/2
$