(4n)(4n+5)(-7)=0

Solution for (4n)(4n+5)(-7)=0 equation:

(4n)(4n+5)(-7)=0

We multiply parentheses ..

4n(-28n-35)=0

We multiply parentheses

-112n^2-140n=0

a = -112; b = -140; c = 0;
Δ = b2-4ac
Δ = -1402-4·(-112)·0
Δ = 19600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{19600}=140$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-140)-140}{2*-112}=\frac{0}{-224}
=0
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-140)+140}{2*-112}=\frac{280}{-224}
=-1+1/4
$