2x^2+6x+9=21

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Solution for 2x^2+6x+9=21 equation:


Simplifying
2x2 + 6x + 9 = 21

Reorder the terms:
9 + 6x + 2x2 = 21

Solving
9 + 6x + 2x2 = 21

Solving for variable 'x'.

Reorder the terms:
9 + -21 + 6x + 2x2 = 21 + -21

Combine like terms: 9 + -21 = -12
-12 + 6x + 2x2 = 21 + -21

Combine like terms: 21 + -21 = 0
-12 + 6x + 2x2 = 0

Factor out the Greatest Common Factor (GCF), '2'.
2(-6 + 3x + x2) = 0

Ignore the factor 2.

Subproblem 1

Set the factor '(-6 + 3x + x2)' equal to zero and attempt to solve: Simplifying -6 + 3x + x2 = 0 Solving -6 + 3x + x2 = 0 Begin completing the square. Move the constant term to the right: Add '6' to each side of the equation. -6 + 3x + 6 + x2 = 0 + 6 Reorder the terms: -6 + 6 + 3x + x2 = 0 + 6 Combine like terms: -6 + 6 = 0 0 + 3x + x2 = 0 + 6 3x + x2 = 0 + 6 Combine like terms: 0 + 6 = 6 3x + x2 = 6 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 = 6 + 2.25 Reorder the terms: 2.25 + 3x + x2 = 6 + 2.25 Combine like terms: 6 + 2.25 = 8.25 2.25 + 3x + x2 = 8.25 Factor a perfect square on the left side: (x + 1.5)(x + 1.5) = 8.25 Calculate the square root of the right side: 2.872281323 Break this problem into two subproblems by setting (x + 1.5) equal to 2.872281323 and -2.872281323.

Subproblem 1

x + 1.5 = 2.872281323 Simplifying x + 1.5 = 2.872281323 Reorder the terms: 1.5 + x = 2.872281323 Solving 1.5 + x = 2.872281323 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 = 2.872281323 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = 2.872281323 + -1.5 x = 2.872281323 + -1.5 Combine like terms: 2.872281323 + -1.5 = 1.372281323 x = 1.372281323 Simplifying x = 1.372281323

Subproblem 2

x + 1.5 = -2.872281323 Simplifying x + 1.5 = -2.872281323 Reorder the terms: 1.5 + x = -2.872281323 Solving 1.5 + x = -2.872281323 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 = -2.872281323 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = -2.872281323 + -1.5 x = -2.872281323 + -1.5 Combine like terms: -2.872281323 + -1.5 = -4.372281323 x = -4.372281323 Simplifying x = -4.372281323

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.372281323, -4.372281323}

Solution

x = {1.372281323, -4.372281323}

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