x2-26x-15=0

Solution for x2-26x-15=0 equation:

x2-26x-15=0

We add all the numbers together, and all the variables

x^2-26x-15=0

a = 1; b = -26; c = -15;
Δ = b2-4ac
Δ = -262-4·1·(-15)
Δ = 736
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{736}=\sqrt{16*46}=\sqrt{16}*\sqrt{46}=4\sqrt{46}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-26)-4\sqrt{46}}{2*1}=\frac{26-4\sqrt{46}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-26)+4\sqrt{46}}{2*1}=\frac{26+4\sqrt{46}}{2}
$