3r^2-18=10r

Solution for 3r^2-18=10r equation:

3r^2-18=10r

We move all terms to the left:

3r^2-18-(10r)=0

a = 3; b = -10; c = -18;
Δ = b2-4ac
Δ = -102-4·3·(-18)
Δ = 316
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{316}=\sqrt{4*79}=\sqrt{4}*\sqrt{79}=2\sqrt{79}$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-2\sqrt{79}}{2*3}=\frac{10-2\sqrt{79}}{6}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+2\sqrt{79}}{2*3}=\frac{10+2\sqrt{79}}{6}
$