r^2+r-1=0

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Solution for r^2+r-1=0 equation: 


Simplifying
r2 + r + -1 = 0

Reorder the terms:
-1 + r + r2 = 0

Solving
-1 + r + r2 = 0

Solving for variable 'r'.

Begin completing the square.

Move the constant term to the right:

Add '1' to each side of the equation.
-1 + r + 1 + r2 = 0 + 1

Reorder the terms:
-1 + 1 + r + r2 = 0 + 1

Combine like terms: -1 + 1 = 0
0 + r + r2 = 0 + 1
r + r2 = 0 + 1

Combine like terms: 0 + 1 = 1
r + r2 = 1

The r term is r.  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.
r + 0.25 + r2 = 1 + 0.25

Reorder the terms:
0.25 + r + r2 = 1 + 0.25

Combine like terms: 1 + 0.25 = 1.25
0.25 + r + r2 = 1.25

Factor a perfect square on the left side:
(r + 0.5)(r + 0.5) = 1.25

Calculate the square root of the right side: 1.118033989

Break this problem into two subproblems by setting 
(r + 0.5) equal to 1.118033989 and -1.118033989.


Subproblem 1
r + 0.5 = 1.118033989

Simplifying
r + 0.5 = 1.118033989

Reorder the terms:
0.5 + r = 1.118033989

Solving
0.5 + r = 1.118033989

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '-0.5' to each side of the equation.
0.5 + -0.5 + r = 1.118033989 + -0.5

Combine like terms: 0.5 + -0.5 = 0.0
0.0 + r = 1.118033989 + -0.5
r = 1.118033989 + -0.5

Combine like terms: 1.118033989 + -0.5 = 0.618033989
r = 0.618033989

Simplifying
r = 0.618033989


Subproblem 2
r + 0.5 = -1.118033989

Simplifying
r + 0.5 = -1.118033989

Reorder the terms:
0.5 + r = -1.118033989

Solving
0.5 + r = -1.118033989

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '-0.5' to each side of the equation.
0.5 + -0.5 + r = -1.118033989 + -0.5

Combine like terms: 0.5 + -0.5 = 0.0
0.0 + r = -1.118033989 + -0.5
r = -1.118033989 + -0.5

Combine like terms: -1.118033989 + -0.5 = -1.618033989
r = -1.618033989

Simplifying
r = -1.618033989


Solution
The solution to the problem is based on the solutions
from the subproblems.
r = {0.618033989, -1.618033989}

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