y2+3y-13.5=0

Solution for y2+3y-13.5=0 equation:

y2+3y-13.5=0

We add all the numbers together, and all the variables

y^2+3y-13.5=0

a = 1; b = 3; c = -13.5;
Δ = b2-4ac
Δ = 32-4·1·(-13.5)
Δ = 63
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{63}=\sqrt{9*7}=\sqrt{9}*\sqrt{7}=3\sqrt{7}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-3\sqrt{7}}{2*1}=\frac{-3-3\sqrt{7}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+3\sqrt{7}}{2*1}=\frac{-3+3\sqrt{7}}{2}
$