r^2+2r=38

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Solution for r^2+2r=38 equation:


Simplifying
r2 + 2r = 38

Reorder the terms:
2r + r2 = 38

Solving
2r + r2 = 38

Solving for variable 'r'.

Reorder the terms:
-38 + 2r + r2 = 38 + -38

Combine like terms: 38 + -38 = 0
-38 + 2r + r2 = 0

Begin completing the square.

Move the constant term to the right:

Add '38' to each side of the equation.
-38 + 2r + 38 + r2 = 0 + 38

Reorder the terms:
-38 + 38 + 2r + r2 = 0 + 38

Combine like terms: -38 + 38 = 0
0 + 2r + r2 = 0 + 38
2r + r2 = 0 + 38

Combine like terms: 0 + 38 = 38
2r + r2 = 38

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 = 38 + 1

Reorder the terms:
1 + 2r + r2 = 38 + 1

Combine like terms: 38 + 1 = 39
1 + 2r + r2 = 39

Factor a perfect square on the left side:
(r + 1)(r + 1) = 39

Calculate the square root of the right side: 6.244997998

Break this problem into two subproblems by setting 
(r + 1) equal to 6.244997998 and -6.244997998.

Subproblem 1

r + 1 = 6.244997998 Simplifying r + 1 = 6.244997998 Reorder the terms: 1 + r = 6.244997998 Solving 1 + r = 6.244997998 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 = 6.244997998 + -1 Combine like terms: 1 + -1 = 0 0 + r = 6.244997998 + -1 r = 6.244997998 + -1 Combine like terms: 6.244997998 + -1 = 5.244997998 r = 5.244997998 Simplifying r = 5.244997998

Subproblem 2

r + 1 = -6.244997998 Simplifying r + 1 = -6.244997998 Reorder the terms: 1 + r = -6.244997998 Solving 1 + r = -6.244997998 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 = -6.244997998 + -1 Combine like terms: 1 + -1 = 0 0 + r = -6.244997998 + -1 r = -6.244997998 + -1 Combine like terms: -6.244997998 + -1 = -7.244997998 r = -7.244997998 Simplifying r = -7.244997998

Solution

The solution to the problem is based on the solutions from the subproblems. r = {5.244997998, -7.244997998}

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