4+5b-2b^2=5

Solution for 4+5b-2b^2=5 equation:

4+5b-2b^2=5

We move all terms to the left:

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

We add all the numbers together, and all the variables

-2b^2+5b-1=0

a = -2; b = 5; c = -1;
Δ = b2-4ac
Δ = 52-4·(-2)·(-1)
Δ = 17
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-\sqrt{17}}{2*-2}=\frac{-5-\sqrt{17}}{-4}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+\sqrt{17}}{2*-2}=\frac{-5+\sqrt{17}}{-4}
$