4r^2+16r-8+7r^2-4r+4+r^2-8r-5=

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Solution for 4r^2+16r-8+7r^2-4r+4+r^2-8r-5= equation:


Simplifying
4r2 + 16r + -8 + 7r2 + -4r + 4 + r2 + -8r + -5 = 0

Reorder the terms:
-8 + 4 + -5 + 16r + -4r + -8r + 4r2 + 7r2 + r2 = 0

Combine like terms: -8 + 4 = -4
-4 + -5 + 16r + -4r + -8r + 4r2 + 7r2 + r2 = 0

Combine like terms: -4 + -5 = -9
-9 + 16r + -4r + -8r + 4r2 + 7r2 + r2 = 0

Combine like terms: 16r + -4r = 12r
-9 + 12r + -8r + 4r2 + 7r2 + r2 = 0

Combine like terms: 12r + -8r = 4r
-9 + 4r + 4r2 + 7r2 + r2 = 0

Combine like terms: 4r2 + 7r2 = 11r2
-9 + 4r + 11r2 + r2 = 0

Combine like terms: 11r2 + r2 = 12r2
-9 + 4r + 12r2 = 0

Solving
-9 + 4r + 12r2 = 0

Solving for variable 'r'.

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

Divide each side by '12'.
-0.75 + 0.3333333333r + r2 = 0

Move the constant term to the right:

Add '0.75' to each side of the equation.
-0.75 + 0.3333333333r + 0.75 + r2 = 0 + 0.75

Reorder the terms:
-0.75 + 0.75 + 0.3333333333r + r2 = 0 + 0.75

Combine like terms: -0.75 + 0.75 = 0.00
0.00 + 0.3333333333r + r2 = 0 + 0.75
0.3333333333r + r2 = 0 + 0.75

Combine like terms: 0 + 0.75 = 0.75
0.3333333333r + r2 = 0.75

The r term is 0.3333333333r.  Take half its coefficient (0.1666666667).
Square it (0.02777777779) and add it to both sides.

Add '0.02777777779' to each side of the equation.
0.3333333333r + 0.02777777779 + r2 = 0.75 + 0.02777777779

Reorder the terms:
0.02777777779 + 0.3333333333r + r2 = 0.75 + 0.02777777779

Combine like terms: 0.75 + 0.02777777779 = 0.77777777779
0.02777777779 + 0.3333333333r + r2 = 0.77777777779

Factor a perfect square on the left side:
(r + 0.1666666667)(r + 0.1666666667) = 0.77777777779

Calculate the square root of the right side: 0.881917104

Break this problem into two subproblems by setting 
(r + 0.1666666667) equal to 0.881917104 and -0.881917104.

Subproblem 1

r + 0.1666666667 = 0.881917104 Simplifying r + 0.1666666667 = 0.881917104 Reorder the terms: 0.1666666667 + r = 0.881917104 Solving 0.1666666667 + r = 0.881917104 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-0.1666666667' to each side of the equation. 0.1666666667 + -0.1666666667 + r = 0.881917104 + -0.1666666667 Combine like terms: 0.1666666667 + -0.1666666667 = 0.0000000000 0.0000000000 + r = 0.881917104 + -0.1666666667 r = 0.881917104 + -0.1666666667 Combine like terms: 0.881917104 + -0.1666666667 = 0.7152504373 r = 0.7152504373 Simplifying r = 0.7152504373

Subproblem 2

r + 0.1666666667 = -0.881917104 Simplifying r + 0.1666666667 = -0.881917104 Reorder the terms: 0.1666666667 + r = -0.881917104 Solving 0.1666666667 + r = -0.881917104 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-0.1666666667' to each side of the equation. 0.1666666667 + -0.1666666667 + r = -0.881917104 + -0.1666666667 Combine like terms: 0.1666666667 + -0.1666666667 = 0.0000000000 0.0000000000 + r = -0.881917104 + -0.1666666667 r = -0.881917104 + -0.1666666667 Combine like terms: -0.881917104 + -0.1666666667 = -1.0485837707 r = -1.0485837707 Simplifying r = -1.0485837707

Solution

The solution to the problem is based on the solutions from the subproblems. r = {0.7152504373, -1.0485837707}

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