r^2+4r-130=0

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Solution for r^2+4r-130=0 equation:


Simplifying
r2 + 4r + -130 = 0

Reorder the terms:
-130 + 4r + r2 = 0

Solving
-130 + 4r + r2 = 0

Solving for variable 'r'.

Begin completing the square.

Move the constant term to the right:

Add '130' to each side of the equation.
-130 + 4r + 130 + r2 = 0 + 130

Reorder the terms:
-130 + 130 + 4r + r2 = 0 + 130

Combine like terms: -130 + 130 = 0
0 + 4r + r2 = 0 + 130
4r + r2 = 0 + 130

Combine like terms: 0 + 130 = 130
4r + r2 = 130

The r term is 4r.  Take half its coefficient (2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
4r + 4 + r2 = 130 + 4

Reorder the terms:
4 + 4r + r2 = 130 + 4

Combine like terms: 130 + 4 = 134
4 + 4r + r2 = 134

Factor a perfect square on the left side:
(r + 2)(r + 2) = 134

Calculate the square root of the right side: 11.575836903

Break this problem into two subproblems by setting 
(r + 2) equal to 11.575836903 and -11.575836903.

Subproblem 1

r + 2 = 11.575836903 Simplifying r + 2 = 11.575836903 Reorder the terms: 2 + r = 11.575836903 Solving 2 + r = 11.575836903 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-2' to each side of the equation. 2 + -2 + r = 11.575836903 + -2 Combine like terms: 2 + -2 = 0 0 + r = 11.575836903 + -2 r = 11.575836903 + -2 Combine like terms: 11.575836903 + -2 = 9.575836903 r = 9.575836903 Simplifying r = 9.575836903

Subproblem 2

r + 2 = -11.575836903 Simplifying r + 2 = -11.575836903 Reorder the terms: 2 + r = -11.575836903 Solving 2 + r = -11.575836903 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-2' to each side of the equation. 2 + -2 + r = -11.575836903 + -2 Combine like terms: 2 + -2 = 0 0 + r = -11.575836903 + -2 r = -11.575836903 + -2 Combine like terms: -11.575836903 + -2 = -13.575836903 r = -13.575836903 Simplifying r = -13.575836903

Solution

The solution to the problem is based on the solutions from the subproblems. r = {9.575836903, -13.575836903}

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