-a^2+a=16

Solution for -a^2+a=16 equation:

Simplifying
-1a2 + a = 16

Reorder the terms:
a + -1a2 = 16

Solving
a + -1a2 = 16

Solving for variable 'a'.

Reorder the terms:
-16 + a + -1a2 = 16 + -16

Combine like terms: 16 + -16 = 0
-16 + a + -1a2 = 0

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

Divide each side by '-1'.
16 + -1a + a2 = 0

Move the constant term to the right:

Add '-16' to each side of the equation.
16 + -1a + -16 + a2 = 0 + -16

Reorder the terms:
16 + -16 + -1a + a2 = 0 + -16

Combine like terms: 16 + -16 = 0
0 + -1a + a2 = 0 + -16
-1a + a2 = 0 + -16

Combine like terms: 0 + -16 = -16
-1a + a2 = -16

The a term is a.  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.
-1a + 0.25 + a2 = -16 + 0.25

Reorder the terms:
0.25 + -1a + a2 = -16 + 0.25

Combine like terms: -16 + 0.25 = -15.75
0.25 + -1a + a2 = -15.75

Factor a perfect square on the left side:
(a + 0.5)(a + 0.5) = -15.75

Can't calculate square root of the right side.

The solution to this equation could not be determined.