21.6y^2-48y-15=0

Solution for 21.6y^2-48y-15=0 equation:

21.6y^2-48y-15=0

a = 21.6; b = -48; c = -15;
Δ = b2-4ac
Δ = -482-4·21.6·(-15)
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-48)-60}{2*21.6}=\frac{-12}{43.2}
=-12/43.2
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-48)+60}{2*21.6}=\frac{108}{43.2}
=2+13.5/27
$