R(x)=-4x^2+1320x

Solution for R(x)=-4x^2+1320x equation:

(R)=-4R^2+1320R

We move all terms to the left:

(R)-(-4R^2+1320R)=0

We get rid of parentheses

4R^2-1320R+R=0

We add all the numbers together, and all the variables

4R^2-1319R=0

a = 4; b = -1319; c = 0;
Δ = b2-4ac
Δ = -13192-4·4·0
Δ = 1739761
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$R_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$R_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1739761}=1319$
$R_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1319)-1319}{2*4}=\frac{0}{8}
=0
$
$R_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1319)+1319}{2*4}=\frac{2638}{8}
=329+3/4
$