55b^2-90b-40=0

Solution for 55b^2-90b-40=0 equation:

55b^2-90b-40=0

a = 55; b = -90; c = -40;
Δ = b2-4ac
Δ = -902-4·55·(-40)
Δ = 16900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16900}=130$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-90)-130}{2*55}=\frac{-40}{110}
=-4/11
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-90)+130}{2*55}=\frac{220}{110}
=2
$