6r^2-12r-20=-9

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Solution for 6r^2-12r-20=-9 equation:


Simplifying
6r2 + -12r + -20 = -9

Reorder the terms:
-20 + -12r + 6r2 = -9

Solving
-20 + -12r + 6r2 = -9

Solving for variable 'r'.

Reorder the terms:
-20 + 9 + -12r + 6r2 = -9 + 9

Combine like terms: -20 + 9 = -11
-11 + -12r + 6r2 = -9 + 9

Combine like terms: -9 + 9 = 0
-11 + -12r + 6r2 = 0

Begin completing the square.  Divide all terms by
6 the coefficient of the squared term: 

Divide each side by '6'.
-1.833333333 + -2r + r2 = 0

Move the constant term to the right:

Add '1.833333333' to each side of the equation.
-1.833333333 + -2r + 1.833333333 + r2 = 0 + 1.833333333

Reorder the terms:
-1.833333333 + 1.833333333 + -2r + r2 = 0 + 1.833333333

Combine like terms: -1.833333333 + 1.833333333 = 0.000000000
0.000000000 + -2r + r2 = 0 + 1.833333333
-2r + r2 = 0 + 1.833333333

Combine like terms: 0 + 1.833333333 = 1.833333333
-2r + r2 = 1.833333333

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 = 1.833333333 + 1

Reorder the terms:
1 + -2r + r2 = 1.833333333 + 1

Combine like terms: 1.833333333 + 1 = 2.833333333
1 + -2r + r2 = 2.833333333

Factor a perfect square on the left side:
(r + -1)(r + -1) = 2.833333333

Calculate the square root of the right side: 1.683250823

Break this problem into two subproblems by setting 
(r + -1) equal to 1.683250823 and -1.683250823.

Subproblem 1

r + -1 = 1.683250823 Simplifying r + -1 = 1.683250823 Reorder the terms: -1 + r = 1.683250823 Solving -1 + r = 1.683250823 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 = 1.683250823 + 1 Combine like terms: -1 + 1 = 0 0 + r = 1.683250823 + 1 r = 1.683250823 + 1 Combine like terms: 1.683250823 + 1 = 2.683250823 r = 2.683250823 Simplifying r = 2.683250823

Subproblem 2

r + -1 = -1.683250823 Simplifying r + -1 = -1.683250823 Reorder the terms: -1 + r = -1.683250823 Solving -1 + r = -1.683250823 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 = -1.683250823 + 1 Combine like terms: -1 + 1 = 0 0 + r = -1.683250823 + 1 r = -1.683250823 + 1 Combine like terms: -1.683250823 + 1 = -0.683250823 r = -0.683250823 Simplifying r = -0.683250823

Solution

The solution to the problem is based on the solutions from the subproblems. r = {2.683250823, -0.683250823}

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