r^2-2r-69=7

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Solution for r^2-2r-69=7 equation:


Simplifying
r2 + -2r + -69 = 7

Reorder the terms:
-69 + -2r + r2 = 7

Solving
-69 + -2r + r2 = 7

Solving for variable 'r'.

Reorder the terms:
-69 + -7 + -2r + r2 = 7 + -7

Combine like terms: -69 + -7 = -76
-76 + -2r + r2 = 7 + -7

Combine like terms: 7 + -7 = 0
-76 + -2r + r2 = 0

Begin completing the square.

Move the constant term to the right:

Add '76' to each side of the equation.
-76 + -2r + 76 + r2 = 0 + 76

Reorder the terms:
-76 + 76 + -2r + r2 = 0 + 76

Combine like terms: -76 + 76 = 0
0 + -2r + r2 = 0 + 76
-2r + r2 = 0 + 76

Combine like terms: 0 + 76 = 76
-2r + r2 = 76

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 = 76 + 1

Reorder the terms:
1 + -2r + r2 = 76 + 1

Combine like terms: 76 + 1 = 77
1 + -2r + r2 = 77

Factor a perfect square on the left side:
(r + -1)(r + -1) = 77

Calculate the square root of the right side: 8.774964387

Break this problem into two subproblems by setting 
(r + -1) equal to 8.774964387 and -8.774964387.

Subproblem 1

r + -1 = 8.774964387 Simplifying r + -1 = 8.774964387 Reorder the terms: -1 + r = 8.774964387 Solving -1 + r = 8.774964387 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 = 8.774964387 + 1 Combine like terms: -1 + 1 = 0 0 + r = 8.774964387 + 1 r = 8.774964387 + 1 Combine like terms: 8.774964387 + 1 = 9.774964387 r = 9.774964387 Simplifying r = 9.774964387

Subproblem 2

r + -1 = -8.774964387 Simplifying r + -1 = -8.774964387 Reorder the terms: -1 + r = -8.774964387 Solving -1 + r = -8.774964387 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 = -8.774964387 + 1 Combine like terms: -1 + 1 = 0 0 + r = -8.774964387 + 1 r = -8.774964387 + 1 Combine like terms: -8.774964387 + 1 = -7.774964387 r = -7.774964387 Simplifying r = -7.774964387

Solution

The solution to the problem is based on the solutions from the subproblems. r = {9.774964387, -7.774964387}

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