3-r^2-8r+16=

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Solution for 3-r^2-8r+16= equation:


Simplifying
3 + -1r2 + -8r + 16 = 0

Reorder the terms:
3 + 16 + -8r + -1r2 = 0

Combine like terms: 3 + 16 = 19
19 + -8r + -1r2 = 0

Solving
19 + -8r + -1r2 = 0

Solving for variable 'r'.

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-19 + 8r + r2 = 0

Move the constant term to the right:

Add '19' to each side of the equation.
-19 + 8r + 19 + r2 = 0 + 19

Reorder the terms:
-19 + 19 + 8r + r2 = 0 + 19

Combine like terms: -19 + 19 = 0
0 + 8r + r2 = 0 + 19
8r + r2 = 0 + 19

Combine like terms: 0 + 19 = 19
8r + r2 = 19

The r term is 8r.  Take half its coefficient (4).
Square it (16) and add it to both sides.

Add '16' to each side of the equation.
8r + 16 + r2 = 19 + 16

Reorder the terms:
16 + 8r + r2 = 19 + 16

Combine like terms: 19 + 16 = 35
16 + 8r + r2 = 35

Factor a perfect square on the left side:
(r + 4)(r + 4) = 35

Calculate the square root of the right side: 5.916079783

Break this problem into two subproblems by setting 
(r + 4) equal to 5.916079783 and -5.916079783.

Subproblem 1

r + 4 = 5.916079783 Simplifying r + 4 = 5.916079783 Reorder the terms: 4 + r = 5.916079783 Solving 4 + r = 5.916079783 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-4' to each side of the equation. 4 + -4 + r = 5.916079783 + -4 Combine like terms: 4 + -4 = 0 0 + r = 5.916079783 + -4 r = 5.916079783 + -4 Combine like terms: 5.916079783 + -4 = 1.916079783 r = 1.916079783 Simplifying r = 1.916079783

Subproblem 2

r + 4 = -5.916079783 Simplifying r + 4 = -5.916079783 Reorder the terms: 4 + r = -5.916079783 Solving 4 + r = -5.916079783 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-4' to each side of the equation. 4 + -4 + r = -5.916079783 + -4 Combine like terms: 4 + -4 = 0 0 + r = -5.916079783 + -4 r = -5.916079783 + -4 Combine like terms: -5.916079783 + -4 = -9.916079783 r = -9.916079783 Simplifying r = -9.916079783

Solution

The solution to the problem is based on the solutions from the subproblems. r = {1.916079783, -9.916079783}

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