x2-30x-4000=0

Solution for x2-30x-4000=0 equation:

x2-30x-4000=0

We add all the numbers together, and all the variables

x^2-30x-4000=0

a = 1; b = -30; c = -4000;
Δ = b2-4ac
Δ = -302-4·1·(-4000)
Δ = 16900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16900}=130$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-130}{2*1}=\frac{-100}{2}
=-50
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+130}{2*1}=\frac{160}{2}
=80
$