-y^2-10y+17=26

Solution for -y^2-10y+17=26 equation:

-y^2-10y+17=26

We move all terms to the left:

-y^2-10y+17-(26)=0

We add all the numbers together, and all the variables

-1y^2-10y-9=0

a = -1; b = -10; c = -9;
Δ = b2-4ac
Δ = -102-4·(-1)·(-9)
Δ = 64
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{64}=8$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-8}{2*-1}=\frac{2}{-2}
=-1
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+8}{2*-1}=\frac{18}{-2}
=-9
$