2b^2-b-91=0

Solution for 2b^2-b-91=0 equation:

2b^2-b-91=0

We add all the numbers together, and all the variables

2b^2-1b-91=0

a = 2; b = -1; c = -91;
Δ = b2-4ac
Δ = -12-4·2·(-91)
Δ = 729
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{729}=27$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-27}{2*2}=\frac{-26}{4}
=-6+1/2
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+27}{2*2}=\frac{28}{4}
=7
$