x^2+9x=28

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Solution for x^2+9x=28 equation:


Simplifying
x2 + 9x = 28

Reorder the terms:
9x + x2 = 28

Solving
9x + x2 = 28

Solving for variable 'x'.

Reorder the terms:
-28 + 9x + x2 = 28 + -28

Combine like terms: 28 + -28 = 0
-28 + 9x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '28' to each side of the equation.
-28 + 9x + 28 + x2 = 0 + 28

Reorder the terms:
-28 + 28 + 9x + x2 = 0 + 28

Combine like terms: -28 + 28 = 0
0 + 9x + x2 = 0 + 28
9x + x2 = 0 + 28

Combine like terms: 0 + 28 = 28
9x + x2 = 28

The x term is 9x.  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.
9x + 20.25 + x2 = 28 + 20.25

Reorder the terms:
20.25 + 9x + x2 = 28 + 20.25

Combine like terms: 28 + 20.25 = 48.25
20.25 + 9x + x2 = 48.25

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

Calculate the square root of the right side: 6.946221995

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

Subproblem 1

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

Subproblem 2

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

Solution

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

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