x^2-9.6x-28.8=0

Solution for x^2-9.6x-28.8=0 equation:

x^2-9.6x-28.8=0

a = 1; b = -9.6; c = -28.8;
Δ = b2-4ac
Δ = -9.62-4·1·(-28.8)
Δ = 207.36
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{-(-9.6)-\sqrt{207.36}}{2*1}=\frac{9.6-\sqrt{207.36}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9.6)+\sqrt{207.36}}{2*1}=\frac{9.6+\sqrt{207.36}}{2}
$