-12r^2-13r+60=0

Solution for -12r^2-13r+60=0 equation:

-12r^2-13r+60=0

a = -12; b = -13; c = +60;
Δ = b2-4ac
Δ = -132-4·(-12)·60
Δ = 3049
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-\sqrt{3049}}{2*-12}=\frac{13-\sqrt{3049}}{-24}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+\sqrt{3049}}{2*-12}=\frac{13+\sqrt{3049}}{-24}
$