9r^2-5r-56=0

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Solution for 9r^2-5r-56=0 equation:


Simplifying
9r2 + -5r + -56 = 0

Reorder the terms:
-56 + -5r + 9r2 = 0

Solving
-56 + -5r + 9r2 = 0

Solving for variable 'r'.

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

Divide each side by '9'.
-6.222222222 + -0.5555555556r + r2 = 0

Move the constant term to the right:

Add '6.222222222' to each side of the equation.
-6.222222222 + -0.5555555556r + 6.222222222 + r2 = 0 + 6.222222222

Reorder the terms:
-6.222222222 + 6.222222222 + -0.5555555556r + r2 = 0 + 6.222222222

Combine like terms: -6.222222222 + 6.222222222 = 0.000000000
0.000000000 + -0.5555555556r + r2 = 0 + 6.222222222
-0.5555555556r + r2 = 0 + 6.222222222

Combine like terms: 0 + 6.222222222 = 6.222222222
-0.5555555556r + r2 = 6.222222222

The r term is -0.5555555556r.  Take half its coefficient (-0.2777777778).
Square it (0.07716049384) and add it to both sides.

Add '0.07716049384' to each side of the equation.
-0.5555555556r + 0.07716049384 + r2 = 6.222222222 + 0.07716049384

Reorder the terms:
0.07716049384 + -0.5555555556r + r2 = 6.222222222 + 0.07716049384

Combine like terms: 6.222222222 + 0.07716049384 = 6.29938271584
0.07716049384 + -0.5555555556r + r2 = 6.29938271584

Factor a perfect square on the left side:
(r + -0.2777777778)(r + -0.2777777778) = 6.29938271584

Calculate the square root of the right side: 2.509857111

Break this problem into two subproblems by setting 
(r + -0.2777777778) equal to 2.509857111 and -2.509857111.

Subproblem 1

r + -0.2777777778 = 2.509857111 Simplifying r + -0.2777777778 = 2.509857111 Reorder the terms: -0.2777777778 + r = 2.509857111 Solving -0.2777777778 + r = 2.509857111 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '0.2777777778' to each side of the equation. -0.2777777778 + 0.2777777778 + r = 2.509857111 + 0.2777777778 Combine like terms: -0.2777777778 + 0.2777777778 = 0.0000000000 0.0000000000 + r = 2.509857111 + 0.2777777778 r = 2.509857111 + 0.2777777778 Combine like terms: 2.509857111 + 0.2777777778 = 2.7876348888 r = 2.7876348888 Simplifying r = 2.7876348888

Subproblem 2

r + -0.2777777778 = -2.509857111 Simplifying r + -0.2777777778 = -2.509857111 Reorder the terms: -0.2777777778 + r = -2.509857111 Solving -0.2777777778 + r = -2.509857111 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '0.2777777778' to each side of the equation. -0.2777777778 + 0.2777777778 + r = -2.509857111 + 0.2777777778 Combine like terms: -0.2777777778 + 0.2777777778 = 0.0000000000 0.0000000000 + r = -2.509857111 + 0.2777777778 r = -2.509857111 + 0.2777777778 Combine like terms: -2.509857111 + 0.2777777778 = -2.2320793332 r = -2.2320793332 Simplifying r = -2.2320793332

Solution

The solution to the problem is based on the solutions from the subproblems. r = {2.7876348888, -2.2320793332}

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