3b^2-8b-18=0

Solution for 3b^2-8b-18=0 equation:

3b^2-8b-18=0

a = 3; b = -8; c = -18;
Δ = b2-4ac
Δ = -82-4·3·(-18)
Δ = 280
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{280}=\sqrt{4*70}=\sqrt{4}*\sqrt{70}=2\sqrt{70}$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-2\sqrt{70}}{2*3}=\frac{8-2\sqrt{70}}{6}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+2\sqrt{70}}{2*3}=\frac{8+2\sqrt{70}}{6}
$