r^2-11=4r

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Solution for r^2-11=4r equation:


Simplifying
r2 + -11 = 4r

Reorder the terms:
-11 + r2 = 4r

Solving
-11 + r2 = 4r

Solving for variable 'r'.

Reorder the terms:
-11 + -4r + r2 = 4r + -4r

Combine like terms: 4r + -4r = 0
-11 + -4r + r2 = 0

Begin completing the square.

Move the constant term to the right:

Add '11' to each side of the equation.
-11 + -4r + 11 + r2 = 0 + 11

Reorder the terms:
-11 + 11 + -4r + r2 = 0 + 11

Combine like terms: -11 + 11 = 0
0 + -4r + r2 = 0 + 11
-4r + r2 = 0 + 11

Combine like terms: 0 + 11 = 11
-4r + r2 = 11

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 = 11 + 4

Reorder the terms:
4 + -4r + r2 = 11 + 4

Combine like terms: 11 + 4 = 15
4 + -4r + r2 = 15

Factor a perfect square on the left side:
(r + -2)(r + -2) = 15

Calculate the square root of the right side: 3.872983346

Break this problem into two subproblems by setting 
(r + -2) equal to 3.872983346 and -3.872983346.

Subproblem 1

r + -2 = 3.872983346 Simplifying r + -2 = 3.872983346 Reorder the terms: -2 + r = 3.872983346 Solving -2 + r = 3.872983346 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 = 3.872983346 + 2 Combine like terms: -2 + 2 = 0 0 + r = 3.872983346 + 2 r = 3.872983346 + 2 Combine like terms: 3.872983346 + 2 = 5.872983346 r = 5.872983346 Simplifying r = 5.872983346

Subproblem 2

r + -2 = -3.872983346 Simplifying r + -2 = -3.872983346 Reorder the terms: -2 + r = -3.872983346 Solving -2 + r = -3.872983346 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 = -3.872983346 + 2 Combine like terms: -2 + 2 = 0 0 + r = -3.872983346 + 2 r = -3.872983346 + 2 Combine like terms: -3.872983346 + 2 = -1.872983346 r = -1.872983346 Simplifying r = -1.872983346

Solution

The solution to the problem is based on the solutions from the subproblems. r = {5.872983346, -1.872983346}

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