(9d+4)(7d+3)=0

Solution for (9d+4)(7d+3)=0 equation:

(9d+4)(7d+3)=0

We multiply parentheses ..

(+63d^2+27d+28d+12)=0

We get rid of parentheses

63d^2+27d+28d+12=0

We add all the numbers together, and all the variables

63d^2+55d+12=0

a = 63; b = 55; c = +12;
Δ = b2-4ac
Δ = 552-4·63·12
Δ = 1
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1}=1$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(55)-1}{2*63}=\frac{-56}{126}
=-4/9
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(55)+1}{2*63}=\frac{-54}{126}
=-3/7
$