s*s-s-16=0

Solution for s*s-s-16=0 equation:

s*s-s-16=0

We add all the numbers together, and all the variables

-1s+s*s-16=0

Wy multiply elements

s^2-1s-16=0

a = 1; b = -1; c = -16;
Δ = b2-4ac
Δ = -12-4·1·(-16)
Δ = 65
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-\sqrt{65}}{2*1}=\frac{1-\sqrt{65}}{2}
$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{65}}{2*1}=\frac{1+\sqrt{65}}{2}
$