k^2+9k-28=0

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Solution for k^2+9k-28=0 equation:


Simplifying
k2 + 9k + -28 = 0

Reorder the terms:
-28 + 9k + k2 = 0

Solving
-28 + 9k + k2 = 0

Solving for variable 'k'.

Begin completing the square.

Move the constant term to the right:

Add '28' to each side of the equation.
-28 + 9k + 28 + k2 = 0 + 28

Reorder the terms:
-28 + 28 + 9k + k2 = 0 + 28

Combine like terms: -28 + 28 = 0
0 + 9k + k2 = 0 + 28
9k + k2 = 0 + 28

Combine like terms: 0 + 28 = 28
9k + k2 = 28

The k term is 9k.  Take half its coefficient (4.5).
Square it (20.25) and add it to both sides.

Add '20.25' to each side of the equation.
9k + 20.25 + k2 = 28 + 20.25

Reorder the terms:
20.25 + 9k + k2 = 28 + 20.25

Combine like terms: 28 + 20.25 = 48.25
20.25 + 9k + k2 = 48.25

Factor a perfect square on the left side:
(k + 4.5)(k + 4.5) = 48.25

Calculate the square root of the right side: 6.946221995

Break this problem into two subproblems by setting 
(k + 4.5) equal to 6.946221995 and -6.946221995.

Subproblem 1

k + 4.5 = 6.946221995 Simplifying k + 4.5 = 6.946221995 Reorder the terms: 4.5 + k = 6.946221995 Solving 4.5 + k = 6.946221995 Solving for variable 'k'. Move all terms containing k to the left, all other terms to the right. Add '-4.5' to each side of the equation. 4.5 + -4.5 + k = 6.946221995 + -4.5 Combine like terms: 4.5 + -4.5 = 0.0 0.0 + k = 6.946221995 + -4.5 k = 6.946221995 + -4.5 Combine like terms: 6.946221995 + -4.5 = 2.446221995 k = 2.446221995 Simplifying k = 2.446221995

Subproblem 2

k + 4.5 = -6.946221995 Simplifying k + 4.5 = -6.946221995 Reorder the terms: 4.5 + k = -6.946221995 Solving 4.5 + k = -6.946221995 Solving for variable 'k'. Move all terms containing k to the left, all other terms to the right. Add '-4.5' to each side of the equation. 4.5 + -4.5 + k = -6.946221995 + -4.5 Combine like terms: 4.5 + -4.5 = 0.0 0.0 + k = -6.946221995 + -4.5 k = -6.946221995 + -4.5 Combine like terms: -6.946221995 + -4.5 = -11.446221995 k = -11.446221995 Simplifying k = -11.446221995

Solution

The solution to the problem is based on the solutions from the subproblems. k = {2.446221995, -11.446221995}

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