X2+6x-400=0

Solution for X2+6x-400=0 equation:

X2+6X-400=0

We add all the numbers together, and all the variables

X^2+6X-400=0

a = 1; b = 6; c = -400;
Δ = b2-4ac
Δ = 62-4·1·(-400)
Δ = 1636
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:

$\sqrt{\Delta}=\sqrt{1636}=\sqrt{4*409}=\sqrt{4}*\sqrt{409}=2\sqrt{409}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-2\sqrt{409}}{2*1}=\frac{-6-2\sqrt{409}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+2\sqrt{409}}{2*1}=\frac{-6+2\sqrt{409}}{2}
$