r^2-39=16r

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Solution for r^2-39=16r equation:


Simplifying
r2 + -39 = 16r

Reorder the terms:
-39 + r2 = 16r

Solving
-39 + r2 = 16r

Solving for variable 'r'.

Reorder the terms:
-39 + -16r + r2 = 16r + -16r

Combine like terms: 16r + -16r = 0
-39 + -16r + r2 = 0

Begin completing the square.

Move the constant term to the right:

Add '39' to each side of the equation.
-39 + -16r + 39 + r2 = 0 + 39

Reorder the terms:
-39 + 39 + -16r + r2 = 0 + 39

Combine like terms: -39 + 39 = 0
0 + -16r + r2 = 0 + 39
-16r + r2 = 0 + 39

Combine like terms: 0 + 39 = 39
-16r + r2 = 39

The r term is -16r.  Take half its coefficient (-8).
Square it (64) and add it to both sides.

Add '64' to each side of the equation.
-16r + 64 + r2 = 39 + 64

Reorder the terms:
64 + -16r + r2 = 39 + 64

Combine like terms: 39 + 64 = 103
64 + -16r + r2 = 103

Factor a perfect square on the left side:
(r + -8)(r + -8) = 103

Calculate the square root of the right side: 10.148891565

Break this problem into two subproblems by setting 
(r + -8) equal to 10.148891565 and -10.148891565.

Subproblem 1

r + -8 = 10.148891565 Simplifying r + -8 = 10.148891565 Reorder the terms: -8 + r = 10.148891565 Solving -8 + r = 10.148891565 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '8' to each side of the equation. -8 + 8 + r = 10.148891565 + 8 Combine like terms: -8 + 8 = 0 0 + r = 10.148891565 + 8 r = 10.148891565 + 8 Combine like terms: 10.148891565 + 8 = 18.148891565 r = 18.148891565 Simplifying r = 18.148891565

Subproblem 2

r + -8 = -10.148891565 Simplifying r + -8 = -10.148891565 Reorder the terms: -8 + r = -10.148891565 Solving -8 + r = -10.148891565 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '8' to each side of the equation. -8 + 8 + r = -10.148891565 + 8 Combine like terms: -8 + 8 = 0 0 + r = -10.148891565 + 8 r = -10.148891565 + 8 Combine like terms: -10.148891565 + 8 = -2.148891565 r = -2.148891565 Simplifying r = -2.148891565

Solution

The solution to the problem is based on the solutions from the subproblems. r = {18.148891565, -2.148891565}

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