y^2-1.2y-3.6=0

Solution for y^2-1.2y-3.6=0 equation:

y^2-1.2y-3.6=0

a = 1; b = -1.2; c = -3.6;
Δ = b2-4ac
Δ = -1.22-4·1·(-3.6)
Δ = 15.84
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1.2)-\sqrt{15.84}}{2*1}=\frac{1.2-\sqrt{15.84}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.2)+\sqrt{15.84}}{2*1}=\frac{1.2+\sqrt{15.84}}{2}
$