R=-9x^2+156x+480

Solution for R=-9x^2+156x+480 equation:

=-9R^2+156R+480

We move all terms to the left:

-(-9R^2+156R+480)=0

We get rid of parentheses

9R^2-156R-480=0

a = 9; b = -156; c = -480;
Δ = b2-4ac
Δ = -1562-4·9·(-480)
Δ = 41616
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$R_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$R_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{41616}=204$
$R_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-156)-204}{2*9}=\frac{-48}{18}
=-2+2/3
$
$R_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-156)+204}{2*9}=\frac{360}{18}
=20
$