(4d+9)(5d+3)=0

Solution for (4d+9)(5d+3)=0 equation:

(4d+9)(5d+3)=0

We multiply parentheses ..

(+20d^2+12d+45d+27)=0

We get rid of parentheses

20d^2+12d+45d+27=0

We add all the numbers together, and all the variables

20d^2+57d+27=0

a = 20; b = 57; c = +27;
Δ = b2-4ac
Δ = 572-4·20·27
Δ = 1089
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1089}=33$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(57)-33}{2*20}=\frac{-90}{40}
=-2+1/4
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(57)+33}{2*20}=\frac{-24}{40}
=-3/5
$