-20=-x+x^2

Solution for -20=-x+x^2 equation:

Simplifying
-20 = -1x + x2

Solving
-20 = -1x + x2

Solving for variable 'x'.

Reorder the terms:
-20 + x + -1x2 = -1x + x + x2 + -1x2

Combine like terms: -1x + x = 0
-20 + x + -1x2 = 0 + x2 + -1x2
-20 + x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
-20 + x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
20 + -1x + x2 = 0

Move the constant term to the right:

Add '-20' to each side of the equation.
20 + -1x + -20 + x2 = 0 + -20

Reorder the terms:
20 + -20 + -1x + x2 = 0 + -20

Combine like terms: 20 + -20 = 0
0 + -1x + x2 = 0 + -20
-1x + x2 = 0 + -20

Combine like terms: 0 + -20 = -20
-1x + x2 = -20

The x term is x.  Take half its coefficient (0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
-1x + 0.25 + x2 = -20 + 0.25

Reorder the terms:
0.25 + -1x + x2 = -20 + 0.25

Combine like terms: -20 + 0.25 = -19.75
0.25 + -1x + x2 = -19.75

Factor a perfect square on the left side:
(x + 0.5)(x + 0.5) = -19.75

Can't calculate square root of the right side.

The solution to this equation could not be determined.