(r-2)(r+8)=50

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Solution for (r-2)(r+8)=50 equation:


Simplifying
(r + -2)(r + 8) = 50

Reorder the terms:
(-2 + r)(r + 8) = 50

Reorder the terms:
(-2 + r)(8 + r) = 50

Multiply (-2 + r) * (8 + r)
(-2(8 + r) + r(8 + r)) = 50
((8 * -2 + r * -2) + r(8 + r)) = 50
((-16 + -2r) + r(8 + r)) = 50
(-16 + -2r + (8 * r + r * r)) = 50
(-16 + -2r + (8r + r2)) = 50

Combine like terms: -2r + 8r = 6r
(-16 + 6r + r2) = 50

Solving
-16 + 6r + r2 = 50

Solving for variable 'r'.

Reorder the terms:
-16 + -50 + 6r + r2 = 50 + -50

Combine like terms: -16 + -50 = -66
-66 + 6r + r2 = 50 + -50

Combine like terms: 50 + -50 = 0
-66 + 6r + r2 = 0

Begin completing the square.

Move the constant term to the right:

Add '66' to each side of the equation.
-66 + 6r + 66 + r2 = 0 + 66

Reorder the terms:
-66 + 66 + 6r + r2 = 0 + 66

Combine like terms: -66 + 66 = 0
0 + 6r + r2 = 0 + 66
6r + r2 = 0 + 66

Combine like terms: 0 + 66 = 66
6r + r2 = 66

The r term is 6r.  Take half its coefficient (3).
Square it (9) and add it to both sides.

Add '9' to each side of the equation.
6r + 9 + r2 = 66 + 9

Reorder the terms:
9 + 6r + r2 = 66 + 9

Combine like terms: 66 + 9 = 75
9 + 6r + r2 = 75

Factor a perfect square on the left side:
(r + 3)(r + 3) = 75

Calculate the square root of the right side: 8.660254038

Break this problem into two subproblems by setting 
(r + 3) equal to 8.660254038 and -8.660254038.

Subproblem 1

r + 3 = 8.660254038 Simplifying r + 3 = 8.660254038 Reorder the terms: 3 + r = 8.660254038 Solving 3 + r = 8.660254038 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-3' to each side of the equation. 3 + -3 + r = 8.660254038 + -3 Combine like terms: 3 + -3 = 0 0 + r = 8.660254038 + -3 r = 8.660254038 + -3 Combine like terms: 8.660254038 + -3 = 5.660254038 r = 5.660254038 Simplifying r = 5.660254038

Subproblem 2

r + 3 = -8.660254038 Simplifying r + 3 = -8.660254038 Reorder the terms: 3 + r = -8.660254038 Solving 3 + r = -8.660254038 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-3' to each side of the equation. 3 + -3 + r = -8.660254038 + -3 Combine like terms: 3 + -3 = 0 0 + r = -8.660254038 + -3 r = -8.660254038 + -3 Combine like terms: -8.660254038 + -3 = -11.660254038 r = -11.660254038 Simplifying r = -11.660254038

Solution

The solution to the problem is based on the solutions from the subproblems. r = {5.660254038, -11.660254038}

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