y^2-5y=9

Solution for y^2-5y=9 equation:

y^2-5y=9

We move all terms to the left:

y^2-5y-(9)=0

a = 1; b = -5; c = -9;
Δ = b2-4ac
Δ = -52-4·1·(-9)
Δ = 61
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{-(-5)-\sqrt{61}}{2*1}=\frac{5-\sqrt{61}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+\sqrt{61}}{2*1}=\frac{5+\sqrt{61}}{2}
$