x2-21x-130=0

Solution for x2-21x-130=0 equation:

x2-21x-130=0

We add all the numbers together, and all the variables

x^2-21x-130=0

a = 1; b = -21; c = -130;
Δ = b2-4ac
Δ = -212-4·1·(-130)
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-21)-31}{2*1}=\frac{-10}{2}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+31}{2*1}=\frac{52}{2}
=26
$