1.25x^2+0.8x=50

Solution for 1.25x^2+0.8x=50 equation:

1.25x^2+0.8x=50

We move all terms to the left:

1.25x^2+0.8x-(50)=0

a = 1.25; b = 0.8; c = -50;
Δ = b2-4ac
Δ = 0.82-4·1.25·(-50)
Δ = 250.64
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0.8)-\sqrt{250.64}}{2*1.25}=\frac{-0.8-\sqrt{250.64}}{2.5}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0.8)+\sqrt{250.64}}{2*1.25}=\frac{-0.8+\sqrt{250.64}}{2.5}
$