k^2-4=-8k

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Solution for k^2-4=-8k equation:


Simplifying
k2 + -4 = -8k

Reorder the terms:
-4 + k2 = -8k

Solving
-4 + k2 = -8k

Solving for variable 'k'.

Reorder the terms:
-4 + 8k + k2 = -8k + 8k

Combine like terms: -8k + 8k = 0
-4 + 8k + k2 = 0

Begin completing the square.

Move the constant term to the right:

Add '4' to each side of the equation.
-4 + 8k + 4 + k2 = 0 + 4

Reorder the terms:
-4 + 4 + 8k + k2 = 0 + 4

Combine like terms: -4 + 4 = 0
0 + 8k + k2 = 0 + 4
8k + k2 = 0 + 4

Combine like terms: 0 + 4 = 4
8k + k2 = 4

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

Add '16' to each side of the equation.
8k + 16 + k2 = 4 + 16

Reorder the terms:
16 + 8k + k2 = 4 + 16

Combine like terms: 4 + 16 = 20
16 + 8k + k2 = 20

Factor a perfect square on the left side:
(k + 4)(k + 4) = 20

Calculate the square root of the right side: 4.472135955

Break this problem into two subproblems by setting 
(k + 4) equal to 4.472135955 and -4.472135955.

Subproblem 1

k + 4 = 4.472135955 Simplifying k + 4 = 4.472135955 Reorder the terms: 4 + k = 4.472135955 Solving 4 + k = 4.472135955 Solving for variable 'k'. Move all terms containing k to the left, all other terms to the right. Add '-4' to each side of the equation. 4 + -4 + k = 4.472135955 + -4 Combine like terms: 4 + -4 = 0 0 + k = 4.472135955 + -4 k = 4.472135955 + -4 Combine like terms: 4.472135955 + -4 = 0.472135955 k = 0.472135955 Simplifying k = 0.472135955

Subproblem 2

k + 4 = -4.472135955 Simplifying k + 4 = -4.472135955 Reorder the terms: 4 + k = -4.472135955 Solving 4 + k = -4.472135955 Solving for variable 'k'. Move all terms containing k to the left, all other terms to the right. Add '-4' to each side of the equation. 4 + -4 + k = -4.472135955 + -4 Combine like terms: 4 + -4 = 0 0 + k = -4.472135955 + -4 k = -4.472135955 + -4 Combine like terms: -4.472135955 + -4 = -8.472135955 k = -8.472135955 Simplifying k = -8.472135955

Solution

The solution to the problem is based on the solutions from the subproblems. k = {0.472135955, -8.472135955}

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