2(2b-4)b=5

Solution for 2(2b-4)b=5 equation:

2(2b-4)b=5

We move all terms to the left:

2(2b-4)b-(5)=0

We multiply parentheses

4b^2-8b-5=0

a = 4; b = -8; c = -5;
Δ = b2-4ac
Δ = -82-4·4·(-5)
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-12}{2*4}=\frac{-4}{8}
=-1/2
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+12}{2*4}=\frac{20}{8}
=2+1/2
$