y^2-6y-17=0

Solution for y^2-6y-17=0 equation:

y^2-6y-17=0

a = 1; b = -6; c = -17;
Δ = b2-4ac
Δ = -62-4·1·(-17)
Δ = 104
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:

$\sqrt{\Delta}=\sqrt{104}=\sqrt{4*26}=\sqrt{4}*\sqrt{26}=2\sqrt{26}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-2\sqrt{26}}{2*1}=\frac{6-2\sqrt{26}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+2\sqrt{26}}{2*1}=\frac{6+2\sqrt{26}}{2}
$