=-2x^2+x-21

Solution for =-2x^2+x-21 equation:

Simplifying
0 = -2x2 + x + -21

Reorder the terms:
0 = -21 + x + -2x2

Solving
0 = -21 + x + -2x2

Solving for variable 'x'.

Combine like terms: 0 + 21 = 21
21 + -1x + 2x2 = -21 + x + -2x2 + 21 + -1x + 2x2

Reorder the terms:
21 + -1x + 2x2 = -21 + 21 + x + -1x + -2x2 + 2x2

Combine like terms: -21 + 21 = 0
21 + -1x + 2x2 = 0 + x + -1x + -2x2 + 2x2
21 + -1x + 2x2 = x + -1x + -2x2 + 2x2

Combine like terms: x + -1x = 0
21 + -1x + 2x2 = 0 + -2x2 + 2x2
21 + -1x + 2x2 = -2x2 + 2x2

Combine like terms: -2x2 + 2x2 = 0
21 + -1x + 2x2 = 0

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

Divide each side by '2'.
10.5 + -0.5x + x2 = 0

Move the constant term to the right:

Add '-10.5' to each side of the equation.
10.5 + -0.5x + -10.5 + x2 = 0 + -10.5

Reorder the terms:
10.5 + -10.5 + -0.5x + x2 = 0 + -10.5

Combine like terms: 10.5 + -10.5 = 0.0
0.0 + -0.5x + x2 = 0 + -10.5
-0.5x + x2 = 0 + -10.5

Combine like terms: 0 + -10.5 = -10.5
-0.5x + x2 = -10.5

The x term is -0.5x.  Take half its coefficient (-0.25).
Square it (0.0625) and add it to both sides.

Add '0.0625' to each side of the equation.
-0.5x + 0.0625 + x2 = -10.5 + 0.0625

Reorder the terms:
0.0625 + -0.5x + x2 = -10.5 + 0.0625

Combine like terms: -10.5 + 0.0625 = -10.4375
0.0625 + -0.5x + x2 = -10.4375

Factor a perfect square on the left side:
(x + -0.25)(x + -0.25) = -10.4375

Can't calculate square root of the right side.

The solution to this equation could not be determined.