3x^2+9x-42=84

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Solution for 3x^2+9x-42=84 equation:


Simplifying
3x2 + 9x + -42 = 84

Reorder the terms:
-42 + 9x + 3x2 = 84

Solving
-42 + 9x + 3x2 = 84

Solving for variable 'x'.

Reorder the terms:
-42 + -84 + 9x + 3x2 = 84 + -84

Combine like terms: -42 + -84 = -126
-126 + 9x + 3x2 = 84 + -84

Combine like terms: 84 + -84 = 0
-126 + 9x + 3x2 = 0

Factor out the Greatest Common Factor (GCF), '3'.
3(-42 + 3x + x2) = 0

Ignore the factor 3.

Subproblem 1

Set the factor '(-42 + 3x + x2)' equal to zero and attempt to solve: Simplifying -42 + 3x + x2 = 0 Solving -42 + 3x + x2 = 0 Begin completing the square. Move the constant term to the right: Add '42' to each side of the equation. -42 + 3x + 42 + x2 = 0 + 42 Reorder the terms: -42 + 42 + 3x + x2 = 0 + 42 Combine like terms: -42 + 42 = 0 0 + 3x + x2 = 0 + 42 3x + x2 = 0 + 42 Combine like terms: 0 + 42 = 42 3x + x2 = 42 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 = 42 + 2.25 Reorder the terms: 2.25 + 3x + x2 = 42 + 2.25 Combine like terms: 42 + 2.25 = 44.25 2.25 + 3x + x2 = 44.25 Factor a perfect square on the left side: (x + 1.5)(x + 1.5) = 44.25 Calculate the square root of the right side: 6.652067348 Break this problem into two subproblems by setting (x + 1.5) equal to 6.652067348 and -6.652067348.

Subproblem 1

x + 1.5 = 6.652067348 Simplifying x + 1.5 = 6.652067348 Reorder the terms: 1.5 + x = 6.652067348 Solving 1.5 + x = 6.652067348 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 = 6.652067348 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = 6.652067348 + -1.5 x = 6.652067348 + -1.5 Combine like terms: 6.652067348 + -1.5 = 5.152067348 x = 5.152067348 Simplifying x = 5.152067348

Subproblem 2

x + 1.5 = -6.652067348 Simplifying x + 1.5 = -6.652067348 Reorder the terms: 1.5 + x = -6.652067348 Solving 1.5 + x = -6.652067348 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 = -6.652067348 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = -6.652067348 + -1.5 x = -6.652067348 + -1.5 Combine like terms: -6.652067348 + -1.5 = -8.152067348 x = -8.152067348 Simplifying x = -8.152067348

Solution

The solution to the problem is based on the solutions from the subproblems. x = {5.152067348, -8.152067348}

Solution

x = {5.152067348, -8.152067348}

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