r^2-2r-2=0

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


Simplifying
r2 + -2r + -2 = 0

Reorder the terms:
-2 + -2r + r2 = 0

Solving
-2 + -2r + r2 = 0

Solving for variable 'r'.

Begin completing the square.

Move the constant term to the right:

Add '2' to each side of the equation.
-2 + -2r + 2 + r2 = 0 + 2

Reorder the terms:
-2 + 2 + -2r + r2 = 0 + 2

Combine like terms: -2 + 2 = 0
0 + -2r + r2 = 0 + 2
-2r + r2 = 0 + 2

Combine like terms: 0 + 2 = 2
-2r + r2 = 2

The r term is -2r.  Take half its coefficient (-1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
-2r + 1 + r2 = 2 + 1

Reorder the terms:
1 + -2r + r2 = 2 + 1

Combine like terms: 2 + 1 = 3
1 + -2r + r2 = 3

Factor a perfect square on the left side:
(r + -1)(r + -1) = 3

Calculate the square root of the right side: 1.732050808

Break this problem into two subproblems by setting 
(r + -1) equal to 1.732050808 and -1.732050808.

Subproblem 1

r + -1 = 1.732050808 Simplifying r + -1 = 1.732050808 Reorder the terms: -1 + r = 1.732050808 Solving -1 + r = 1.732050808 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '1' to each side of the equation. -1 + 1 + r = 1.732050808 + 1 Combine like terms: -1 + 1 = 0 0 + r = 1.732050808 + 1 r = 1.732050808 + 1 Combine like terms: 1.732050808 + 1 = 2.732050808 r = 2.732050808 Simplifying r = 2.732050808

Subproblem 2

r + -1 = -1.732050808 Simplifying r + -1 = -1.732050808 Reorder the terms: -1 + r = -1.732050808 Solving -1 + r = -1.732050808 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '1' to each side of the equation. -1 + 1 + r = -1.732050808 + 1 Combine like terms: -1 + 1 = 0 0 + r = -1.732050808 + 1 r = -1.732050808 + 1 Combine like terms: -1.732050808 + 1 = -0.732050808 r = -0.732050808 Simplifying r = -0.732050808

Solution

The solution to the problem is based on the solutions from the subproblems. r = {2.732050808, -0.732050808}

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