2a^2-2a-1=0

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Solution for 2a^2-2a-1=0 equation:


Simplifying
2a2 + -2a + -1 = 0

Reorder the terms:
-1 + -2a + 2a2 = 0

Solving
-1 + -2a + 2a2 = 0

Solving for variable 'a'.

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

Divide each side by '2'.
-0.5 + -1a + a2 = 0

Move the constant term to the right:

Add '0.5' to each side of the equation.
-0.5 + -1a + 0.5 + a2 = 0 + 0.5

Reorder the terms:
-0.5 + 0.5 + -1a + a2 = 0 + 0.5

Combine like terms: -0.5 + 0.5 = 0.0
0.0 + -1a + a2 = 0 + 0.5
-1a + a2 = 0 + 0.5

Combine like terms: 0 + 0.5 = 0.5
-1a + a2 = 0.5

The a term is -1a.  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 = 0.5 + 0.25

Reorder the terms:
0.25 + -1a + a2 = 0.5 + 0.25

Combine like terms: 0.5 + 0.25 = 0.75
0.25 + -1a + a2 = 0.75

Factor a perfect square on the left side:
(a + -0.5)(a + -0.5) = 0.75

Calculate the square root of the right side: 0.866025404

Break this problem into two subproblems by setting 
(a + -0.5) equal to 0.866025404 and -0.866025404.

Subproblem 1

a + -0.5 = 0.866025404 Simplifying a + -0.5 = 0.866025404 Reorder the terms: -0.5 + a = 0.866025404 Solving -0.5 + a = 0.866025404 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '0.5' to each side of the equation. -0.5 + 0.5 + a = 0.866025404 + 0.5 Combine like terms: -0.5 + 0.5 = 0.0 0.0 + a = 0.866025404 + 0.5 a = 0.866025404 + 0.5 Combine like terms: 0.866025404 + 0.5 = 1.366025404 a = 1.366025404 Simplifying a = 1.366025404

Subproblem 2

a + -0.5 = -0.866025404 Simplifying a + -0.5 = -0.866025404 Reorder the terms: -0.5 + a = -0.866025404 Solving -0.5 + a = -0.866025404 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '0.5' to each side of the equation. -0.5 + 0.5 + a = -0.866025404 + 0.5 Combine like terms: -0.5 + 0.5 = 0.0 0.0 + a = -0.866025404 + 0.5 a = -0.866025404 + 0.5 Combine like terms: -0.866025404 + 0.5 = -0.366025404 a = -0.366025404 Simplifying a = -0.366025404

Solution

The solution to the problem is based on the solutions from the subproblems. a = {1.366025404, -0.366025404}

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