(9d-1)(7d-5)=0

Solution for (9d-1)(7d-5)=0 equation:

(9d-1)(7d-5)=0

We multiply parentheses ..

(+63d^2-45d-7d+5)=0

We get rid of parentheses

63d^2-45d-7d+5=0

We add all the numbers together, and all the variables

63d^2-52d+5=0

a = 63; b = -52; c = +5;
Δ = b2-4ac
Δ = -522-4·63·5
Δ = 1444
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1444}=38$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-52)-38}{2*63}=\frac{14}{126}
=1/9
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-52)+38}{2*63}=\frac{90}{126}
=5/7
$