7r^2+5r-11=0

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Solution for 7r^2+5r-11=0 equation:


Simplifying
7r2 + 5r + -11 = 0

Reorder the terms:
-11 + 5r + 7r2 = 0

Solving
-11 + 5r + 7r2 = 0

Solving for variable 'r'.

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

Divide each side by '7'.
-1.571428571 + 0.7142857143r + r2 = 0

Move the constant term to the right:

Add '1.571428571' to each side of the equation.
-1.571428571 + 0.7142857143r + 1.571428571 + r2 = 0 + 1.571428571

Reorder the terms:
-1.571428571 + 1.571428571 + 0.7142857143r + r2 = 0 + 1.571428571

Combine like terms: -1.571428571 + 1.571428571 = 0.000000000
0.000000000 + 0.7142857143r + r2 = 0 + 1.571428571
0.7142857143r + r2 = 0 + 1.571428571

Combine like terms: 0 + 1.571428571 = 1.571428571
0.7142857143r + r2 = 1.571428571

The r term is 0.7142857143r.  Take half its coefficient (0.3571428572).
Square it (0.1275510204) and add it to both sides.

Add '0.1275510204' to each side of the equation.
0.7142857143r + 0.1275510204 + r2 = 1.571428571 + 0.1275510204

Reorder the terms:
0.1275510204 + 0.7142857143r + r2 = 1.571428571 + 0.1275510204

Combine like terms: 1.571428571 + 0.1275510204 = 1.6989795914
0.1275510204 + 0.7142857143r + r2 = 1.6989795914

Factor a perfect square on the left side:
(r + 0.3571428572)(r + 0.3571428572) = 1.6989795914

Calculate the square root of the right side: 1.303449113

Break this problem into two subproblems by setting 
(r + 0.3571428572) equal to 1.303449113 and -1.303449113.

Subproblem 1

r + 0.3571428572 = 1.303449113 Simplifying r + 0.3571428572 = 1.303449113 Reorder the terms: 0.3571428572 + r = 1.303449113 Solving 0.3571428572 + r = 1.303449113 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-0.3571428572' to each side of the equation. 0.3571428572 + -0.3571428572 + r = 1.303449113 + -0.3571428572 Combine like terms: 0.3571428572 + -0.3571428572 = 0.0000000000 0.0000000000 + r = 1.303449113 + -0.3571428572 r = 1.303449113 + -0.3571428572 Combine like terms: 1.303449113 + -0.3571428572 = 0.9463062558 r = 0.9463062558 Simplifying r = 0.9463062558

Subproblem 2

r + 0.3571428572 = -1.303449113 Simplifying r + 0.3571428572 = -1.303449113 Reorder the terms: 0.3571428572 + r = -1.303449113 Solving 0.3571428572 + r = -1.303449113 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-0.3571428572' to each side of the equation. 0.3571428572 + -0.3571428572 + r = -1.303449113 + -0.3571428572 Combine like terms: 0.3571428572 + -0.3571428572 = 0.0000000000 0.0000000000 + r = -1.303449113 + -0.3571428572 r = -1.303449113 + -0.3571428572 Combine like terms: -1.303449113 + -0.3571428572 = -1.6605919702 r = -1.6605919702 Simplifying r = -1.6605919702

Solution

The solution to the problem is based on the solutions from the subproblems. r = {0.9463062558, -1.6605919702}

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