3r2-12r=36

Solution for 3r2-12r=36 equation:

3r^2-12r=36

We move all terms to the left:

3r^2-12r-(36)=0

a = 3; b = -12; c = -36;
Δ = b2-4ac
Δ = -122-4·3·(-36)
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-24}{2*3}=\frac{-12}{6}
=-2
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+24}{2*3}=\frac{36}{6}
=6
$