y2-5y=4

Solution for y2-5y=4 equation:

y2-5y=4

We move all terms to the left:

y2-5y-(4)=0

We add all the numbers together, and all the variables

y^2-5y-4=0

a = 1; b = -5; c = -4;
Δ = b2-4ac
Δ = -52-4·1·(-4)
Δ = 41
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{41}}{2*1}=\frac{5-\sqrt{41}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+\sqrt{41}}{2*1}=\frac{5+\sqrt{41}}{2}
$