1.25x^2-8x-16=0

Solution for 1.25x^2-8x-16=0 equation:

1.25x^2-8x-16=0

a = 1.25; b = -8; c = -16;
Δ = b2-4ac
Δ = -82-4·1.25·(-16)
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-12}{2*1.25}=\frac{-4}{2.5}
=-1+1/1.66666666667
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+12}{2*1.25}=\frac{20}{2.5}
=8
$