9b^2-71b+56=0

Solution for 9b^2-71b+56=0 equation:

9b^2-71b+56=0

a = 9; b = -71; c = +56;
Δ = b2-4ac
Δ = -712-4·9·56
Δ = 3025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3025}=55$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-71)-55}{2*9}=\frac{16}{18}
=8/9
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-71)+55}{2*9}=\frac{126}{18}
=7
$