x2-17x-12.5=0

Solution for x2-17x-12.5=0 equation:

x2-17x-12.5=0

We add all the numbers together, and all the variables

x^2-17x-12.5=0

a = 1; b = -17; c = -12.5;
Δ = b2-4ac
Δ = -172-4·1·(-12.5)
Δ = 339
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-17)-\sqrt{339}}{2*1}=\frac{17-\sqrt{339}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-17)+\sqrt{339}}{2*1}=\frac{17+\sqrt{339}}{2}
$