y^2+5y-1=1.25

Solution for y^2+5y-1=1.25 equation:

y^2+5y-1=1.25

We move all terms to the left:

y^2+5y-1-(1.25)=0

We add all the numbers together, and all the variables

y^2+5y-2.25=0

a = 1; b = 5; c = -2.25;
Δ = b2-4ac
Δ = 52-4·1·(-2.25)
Δ = 34
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{34}}{2*1}=\frac{-5-\sqrt{34}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+\sqrt{34}}{2*1}=\frac{-5+\sqrt{34}}{2}
$