-2b-4b^2=-0.75

Solution for -2b-4b^2=-0.75 equation:

-2b-4b^2=-0.75

We move all terms to the left:

-2b-4b^2-(-0.75)=0

We add all the numbers together, and all the variables

-4b^2-2b+0.75=0

a = -4; b = -2; c = +0.75;
Δ = b2-4ac
Δ = -22-4·(-4)·0.75
Δ = 16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16}=4$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-4}{2*-4}=\frac{-2}{-8}
=1/4
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+4}{2*-4}=\frac{6}{-8}
=-3/4
$