(7n+3)(8n-3)=0

Solution for (7n+3)(8n-3)=0 equation:

(7n+3)(8n-3)=0

We multiply parentheses ..

(+56n^2-21n+24n-9)=0

We get rid of parentheses

56n^2-21n+24n-9=0

We add all the numbers together, and all the variables

56n^2+3n-9=0

a = 56; b = 3; c = -9;
Δ = b2-4ac
Δ = 32-4·56·(-9)
Δ = 2025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2025}=45$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-45}{2*56}=\frac{-48}{112}
=-3/7
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+45}{2*56}=\frac{42}{112}
=3/8
$