x^2-15x-221=0

Solution for x^2-15x-221=0 equation:

x^2-15x-221=0

a = 1; b = -15; c = -221;
Δ = b2-4ac
Δ = -152-4·1·(-221)
Δ = 1109
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{-(-15)-\sqrt{1109}}{2*1}=\frac{15-\sqrt{1109}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+\sqrt{1109}}{2*1}=\frac{15+\sqrt{1109}}{2}
$