15b^2-5b-70=0

Solution for 15b^2-5b-70=0 equation:

15b^2-5b-70=0

a = 15; b = -5; c = -70;
Δ = b2-4ac
Δ = -52-4·15·(-70)
Δ = 4225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4225}=65$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-65}{2*15}=\frac{-60}{30}
=-2
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+65}{2*15}=\frac{70}{30}
=2+1/3
$