9-(8r^2+2r)=0

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Solution for 9-(8r^2+2r)=0 equation:


Simplifying
9 + -1(8r2 + 2r) = 0

Reorder the terms:
9 + -1(2r + 8r2) = 0
9 + (2r * -1 + 8r2 * -1) = 0
9 + (-2r + -8r2) = 0

Solving
9 + -2r + -8r2 = 0

Solving for variable 'r'.

Begin completing the square.  Divide all terms by
-8 the coefficient of the squared term: 

Divide each side by '-8'.
-1.125 + 0.25r + r2 = 0

Move the constant term to the right:

Add '1.125' to each side of the equation.
-1.125 + 0.25r + 1.125 + r2 = 0 + 1.125

Reorder the terms:
-1.125 + 1.125 + 0.25r + r2 = 0 + 1.125

Combine like terms: -1.125 + 1.125 = 0.000
0.000 + 0.25r + r2 = 0 + 1.125
0.25r + r2 = 0 + 1.125

Combine like terms: 0 + 1.125 = 1.125
0.25r + r2 = 1.125

The r term is 0.25r.  Take half its coefficient (0.125).
Square it (0.015625) and add it to both sides.

Add '0.015625' to each side of the equation.
0.25r + 0.015625 + r2 = 1.125 + 0.015625

Reorder the terms:
0.015625 + 0.25r + r2 = 1.125 + 0.015625

Combine like terms: 1.125 + 0.015625 = 1.140625
0.015625 + 0.25r + r2 = 1.140625

Factor a perfect square on the left side:
(r + 0.125)(r + 0.125) = 1.140625

Calculate the square root of the right side: 1.068000468

Break this problem into two subproblems by setting 
(r + 0.125) equal to 1.068000468 and -1.068000468.

Subproblem 1

r + 0.125 = 1.068000468 Simplifying r + 0.125 = 1.068000468 Reorder the terms: 0.125 + r = 1.068000468 Solving 0.125 + r = 1.068000468 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-0.125' to each side of the equation. 0.125 + -0.125 + r = 1.068000468 + -0.125 Combine like terms: 0.125 + -0.125 = 0.000 0.000 + r = 1.068000468 + -0.125 r = 1.068000468 + -0.125 Combine like terms: 1.068000468 + -0.125 = 0.943000468 r = 0.943000468 Simplifying r = 0.943000468

Subproblem 2

r + 0.125 = -1.068000468 Simplifying r + 0.125 = -1.068000468 Reorder the terms: 0.125 + r = -1.068000468 Solving 0.125 + r = -1.068000468 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-0.125' to each side of the equation. 0.125 + -0.125 + r = -1.068000468 + -0.125 Combine like terms: 0.125 + -0.125 = 0.000 0.000 + r = -1.068000468 + -0.125 r = -1.068000468 + -0.125 Combine like terms: -1.068000468 + -0.125 = -1.193000468 r = -1.193000468 Simplifying r = -1.193000468

Solution

The solution to the problem is based on the solutions from the subproblems. r = {0.943000468, -1.193000468}

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