-x2-4x+1=0

Solution for -x2-4x+1=0 equation:

-x2-4x+1=0

We add all the numbers together, and all the variables

-1x^2-4x+1=0

a = -1; b = -4; c = +1;
Δ = b2-4ac
Δ = -42-4·(-1)·1
Δ = 20
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:

$\sqrt{\Delta}=\sqrt{20}=\sqrt{4*5}=\sqrt{4}*\sqrt{5}=2\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-2\sqrt{5}}{2*-1}=\frac{4-2\sqrt{5}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+2\sqrt{5}}{2*-1}=\frac{4+2\sqrt{5}}{-2}
$