(5-2d)(3+4d)=0

Solution for (5-2d)(3+4d)=0 equation:

(5-2d)(3+4d)=0

We add all the numbers together, and all the variables

(-2d+5)(4d+3)=0

We multiply parentheses ..

(-8d^2-6d+20d+15)=0

We get rid of parentheses

-8d^2-6d+20d+15=0

We add all the numbers together, and all the variables

-8d^2+14d+15=0

a = -8; b = 14; c = +15;
Δ = b2-4ac
Δ = 142-4·(-8)·15
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(14)-26}{2*-8}=\frac{-40}{-16}
=2+1/2
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(14)+26}{2*-8}=\frac{12}{-16}
=-3/4
$