x^2-0.4x=96

Solution for x^2-0.4x=96 equation:

x^2-0.4x=96

We move all terms to the left:

x^2-0.4x-(96)=0

a = 1; b = -0.4; c = -96;
Δ = b2-4ac
Δ = -0.42-4·1·(-96)
Δ = 384.16
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{-(-0.4)-\sqrt{384.16}}{2*1}=\frac{0.4-\sqrt{384.16}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.4)+\sqrt{384.16}}{2*1}=\frac{0.4+\sqrt{384.16}}{2}
$