7b^2-20b-3=0

Solution for 7b^2-20b-3=0 equation:

7b^2-20b-3=0

a = 7; b = -20; c = -3;
Δ = b2-4ac
Δ = -202-4·7·(-3)
Δ = 484
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{484}=22$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-22}{2*7}=\frac{-2}{14}
=-1/7
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+22}{2*7}=\frac{42}{14}
=3
$