13.2x^2+21.6x-4.8=0

Solution for 13.2x^2+21.6x-4.8=0 equation:

13.2x^2+21.6x-4.8=0

a = 13.2; b = 21.6; c = -4.8;
Δ = b2-4ac
Δ = 21.62-4·13.2·(-4.8)
Δ = 720
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{720}=\sqrt{144*5}=\sqrt{144}*\sqrt{5}=12\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21.6)-12\sqrt{5}}{2*13.2}=\frac{-21.6-12\sqrt{5}}{26.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21.6)+12\sqrt{5}}{2*13.2}=\frac{-21.6+12\sqrt{5}}{26.4}
$