3x^2+9x=81

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Solution for 3x^2+9x=81 equation:


Simplifying
3x2 + 9x = 81

Reorder the terms:
9x + 3x2 = 81

Solving
9x + 3x2 = 81

Solving for variable 'x'.

Reorder the terms:
-81 + 9x + 3x2 = 81 + -81

Combine like terms: 81 + -81 = 0
-81 + 9x + 3x2 = 0

Factor out the Greatest Common Factor (GCF), '3'.
3(-27 + 3x + x2) = 0

Ignore the factor 3.

Subproblem 1

Set the factor '(-27 + 3x + x2)' equal to zero and attempt to solve: Simplifying -27 + 3x + x2 = 0 Solving -27 + 3x + x2 = 0 Begin completing the square. Move the constant term to the right: Add '27' to each side of the equation. -27 + 3x + 27 + x2 = 0 + 27 Reorder the terms: -27 + 27 + 3x + x2 = 0 + 27 Combine like terms: -27 + 27 = 0 0 + 3x + x2 = 0 + 27 3x + x2 = 0 + 27 Combine like terms: 0 + 27 = 27 3x + x2 = 27 The x term is 3x. Take half its coefficient (1.5). Square it (2.25) and add it to both sides. Add '2.25' to each side of the equation. 3x + 2.25 + x2 = 27 + 2.25 Reorder the terms: 2.25 + 3x + x2 = 27 + 2.25 Combine like terms: 27 + 2.25 = 29.25 2.25 + 3x + x2 = 29.25 Factor a perfect square on the left side: (x + 1.5)(x + 1.5) = 29.25 Calculate the square root of the right side: 5.408326913 Break this problem into two subproblems by setting (x + 1.5) equal to 5.408326913 and -5.408326913.

Subproblem 1

x + 1.5 = 5.408326913 Simplifying x + 1.5 = 5.408326913 Reorder the terms: 1.5 + x = 5.408326913 Solving 1.5 + x = 5.408326913 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.5' to each side of the equation. 1.5 + -1.5 + x = 5.408326913 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = 5.408326913 + -1.5 x = 5.408326913 + -1.5 Combine like terms: 5.408326913 + -1.5 = 3.908326913 x = 3.908326913 Simplifying x = 3.908326913

Subproblem 2

x + 1.5 = -5.408326913 Simplifying x + 1.5 = -5.408326913 Reorder the terms: 1.5 + x = -5.408326913 Solving 1.5 + x = -5.408326913 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.5' to each side of the equation. 1.5 + -1.5 + x = -5.408326913 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = -5.408326913 + -1.5 x = -5.408326913 + -1.5 Combine like terms: -5.408326913 + -1.5 = -6.908326913 x = -6.908326913 Simplifying x = -6.908326913

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.908326913, -6.908326913}

Solution

x = {3.908326913, -6.908326913}

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