k^2+9k+4=0

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Solution for k^2+9k+4=0 equation:


Simplifying
k2 + 9k + 4 = 0

Reorder the terms:
4 + 9k + k2 = 0

Solving
4 + 9k + k2 = 0

Solving for variable 'k'.

Begin completing the square.

Move the constant term to the right:

Add '-4' to each side of the equation.
4 + 9k + -4 + k2 = 0 + -4

Reorder the terms:
4 + -4 + 9k + k2 = 0 + -4

Combine like terms: 4 + -4 = 0
0 + 9k + k2 = 0 + -4
9k + k2 = 0 + -4

Combine like terms: 0 + -4 = -4
9k + k2 = -4

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 = -4 + 20.25

Reorder the terms:
20.25 + 9k + k2 = -4 + 20.25

Combine like terms: -4 + 20.25 = 16.25
20.25 + 9k + k2 = 16.25

Factor a perfect square on the left side:
(k + 4.5)(k + 4.5) = 16.25

Calculate the square root of the right side: 4.031128874

Break this problem into two subproblems by setting 
(k + 4.5) equal to 4.031128874 and -4.031128874.

Subproblem 1

k + 4.5 = 4.031128874 Simplifying k + 4.5 = 4.031128874 Reorder the terms: 4.5 + k = 4.031128874 Solving 4.5 + k = 4.031128874 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 = 4.031128874 + -4.5 Combine like terms: 4.5 + -4.5 = 0.0 0.0 + k = 4.031128874 + -4.5 k = 4.031128874 + -4.5 Combine like terms: 4.031128874 + -4.5 = -0.468871126 k = -0.468871126 Simplifying k = -0.468871126

Subproblem 2

k + 4.5 = -4.031128874 Simplifying k + 4.5 = -4.031128874 Reorder the terms: 4.5 + k = -4.031128874 Solving 4.5 + k = -4.031128874 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 = -4.031128874 + -4.5 Combine like terms: 4.5 + -4.5 = 0.0 0.0 + k = -4.031128874 + -4.5 k = -4.031128874 + -4.5 Combine like terms: -4.031128874 + -4.5 = -8.531128874 k = -8.531128874 Simplifying k = -8.531128874

Solution

The solution to the problem is based on the solutions from the subproblems. k = {-0.468871126, -8.531128874}

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