3r^2+12r=23

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Solution for 3r^2+12r=23 equation:


Simplifying
3r2 + 12r = 23

Reorder the terms:
12r + 3r2 = 23

Solving
12r + 3r2 = 23

Solving for variable 'r'.

Reorder the terms:
-23 + 12r + 3r2 = 23 + -23

Combine like terms: 23 + -23 = 0
-23 + 12r + 3r2 = 0

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

Divide each side by '3'.
-7.666666667 + 4r + r2 = 0

Move the constant term to the right:

Add '7.666666667' to each side of the equation.
-7.666666667 + 4r + 7.666666667 + r2 = 0 + 7.666666667

Reorder the terms:
-7.666666667 + 7.666666667 + 4r + r2 = 0 + 7.666666667

Combine like terms: -7.666666667 + 7.666666667 = 0.000000000
0.000000000 + 4r + r2 = 0 + 7.666666667
4r + r2 = 0 + 7.666666667

Combine like terms: 0 + 7.666666667 = 7.666666667
4r + r2 = 7.666666667

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 = 7.666666667 + 4

Reorder the terms:
4 + 4r + r2 = 7.666666667 + 4

Combine like terms: 7.666666667 + 4 = 11.666666667
4 + 4r + r2 = 11.666666667

Factor a perfect square on the left side:
(r + 2)(r + 2) = 11.666666667

Calculate the square root of the right side: 3.415650255

Break this problem into two subproblems by setting 
(r + 2) equal to 3.415650255 and -3.415650255.

Subproblem 1

r + 2 = 3.415650255 Simplifying r + 2 = 3.415650255 Reorder the terms: 2 + r = 3.415650255 Solving 2 + r = 3.415650255 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 = 3.415650255 + -2 Combine like terms: 2 + -2 = 0 0 + r = 3.415650255 + -2 r = 3.415650255 + -2 Combine like terms: 3.415650255 + -2 = 1.415650255 r = 1.415650255 Simplifying r = 1.415650255

Subproblem 2

r + 2 = -3.415650255 Simplifying r + 2 = -3.415650255 Reorder the terms: 2 + r = -3.415650255 Solving 2 + r = -3.415650255 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 = -3.415650255 + -2 Combine like terms: 2 + -2 = 0 0 + r = -3.415650255 + -2 r = -3.415650255 + -2 Combine like terms: -3.415650255 + -2 = -5.415650255 r = -5.415650255 Simplifying r = -5.415650255

Solution

The solution to the problem is based on the solutions from the subproblems. r = {1.415650255, -5.415650255}

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