r^2-2r-30=0

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Solution for r^2-2r-30=0 equation:


Simplifying
r2 + -2r + -30 = 0

Reorder the terms:
-30 + -2r + r2 = 0

Solving
-30 + -2r + r2 = 0

Solving for variable 'r'.

Begin completing the square.

Move the constant term to the right:

Add '30' to each side of the equation.
-30 + -2r + 30 + r2 = 0 + 30

Reorder the terms:
-30 + 30 + -2r + r2 = 0 + 30

Combine like terms: -30 + 30 = 0
0 + -2r + r2 = 0 + 30
-2r + r2 = 0 + 30

Combine like terms: 0 + 30 = 30
-2r + r2 = 30

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 = 30 + 1

Reorder the terms:
1 + -2r + r2 = 30 + 1

Combine like terms: 30 + 1 = 31
1 + -2r + r2 = 31

Factor a perfect square on the left side:
(r + -1)(r + -1) = 31

Calculate the square root of the right side: 5.567764363

Break this problem into two subproblems by setting 
(r + -1) equal to 5.567764363 and -5.567764363.

Subproblem 1

r + -1 = 5.567764363 Simplifying r + -1 = 5.567764363 Reorder the terms: -1 + r = 5.567764363 Solving -1 + r = 5.567764363 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 = 5.567764363 + 1 Combine like terms: -1 + 1 = 0 0 + r = 5.567764363 + 1 r = 5.567764363 + 1 Combine like terms: 5.567764363 + 1 = 6.567764363 r = 6.567764363 Simplifying r = 6.567764363

Subproblem 2

r + -1 = -5.567764363 Simplifying r + -1 = -5.567764363 Reorder the terms: -1 + r = -5.567764363 Solving -1 + r = -5.567764363 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 = -5.567764363 + 1 Combine like terms: -1 + 1 = 0 0 + r = -5.567764363 + 1 r = -5.567764363 + 1 Combine like terms: -5.567764363 + 1 = -4.567764363 r = -4.567764363 Simplifying r = -4.567764363

Solution

The solution to the problem is based on the solutions from the subproblems. r = {6.567764363, -4.567764363}

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