(5d+4)(2d+9)=0

Solution for (5d+4)(2d+9)=0 equation:

(5d+4)(2d+9)=0

We multiply parentheses ..

(+10d^2+45d+8d+36)=0

We get rid of parentheses

10d^2+45d+8d+36=0

We add all the numbers together, and all the variables

10d^2+53d+36=0

a = 10; b = 53; c = +36;
Δ = b2-4ac
Δ = 532-4·10·36
Δ = 1369
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1369}=37$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(53)-37}{2*10}=\frac{-90}{20}
=-4+1/2
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(53)+37}{2*10}=\frac{-16}{20}
=-4/5
$