7x^2+21x+7=0

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Solution for 7x^2+21x+7=0 equation:


Simplifying
7x2 + 21x + 7 = 0

Reorder the terms:
7 + 21x + 7x2 = 0

Solving
7 + 21x + 7x2 = 0

Solving for variable 'x'.

Factor out the Greatest Common Factor (GCF), '7'.
7(1 + 3x + x2) = 0

Ignore the factor 7.

Subproblem 1

Set the factor '(1 + 3x + x2)' equal to zero and attempt to solve: Simplifying 1 + 3x + x2 = 0 Solving 1 + 3x + x2 = 0 Begin completing the square. Move the constant term to the right: Add '-1' to each side of the equation. 1 + 3x + -1 + x2 = 0 + -1 Reorder the terms: 1 + -1 + 3x + x2 = 0 + -1 Combine like terms: 1 + -1 = 0 0 + 3x + x2 = 0 + -1 3x + x2 = 0 + -1 Combine like terms: 0 + -1 = -1 3x + x2 = -1 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 = -1 + 2.25 Reorder the terms: 2.25 + 3x + x2 = -1 + 2.25 Combine like terms: -1 + 2.25 = 1.25 2.25 + 3x + x2 = 1.25 Factor a perfect square on the left side: (x + 1.5)(x + 1.5) = 1.25 Calculate the square root of the right side: 1.118033989 Break this problem into two subproblems by setting (x + 1.5) equal to 1.118033989 and -1.118033989.

Subproblem 1

x + 1.5 = 1.118033989 Simplifying x + 1.5 = 1.118033989 Reorder the terms: 1.5 + x = 1.118033989 Solving 1.5 + x = 1.118033989 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 = 1.118033989 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = 1.118033989 + -1.5 x = 1.118033989 + -1.5 Combine like terms: 1.118033989 + -1.5 = -0.381966011 x = -0.381966011 Simplifying x = -0.381966011

Subproblem 2

x + 1.5 = -1.118033989 Simplifying x + 1.5 = -1.118033989 Reorder the terms: 1.5 + x = -1.118033989 Solving 1.5 + x = -1.118033989 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 = -1.118033989 + -1.5 Combine like terms: 1.5 + -1.5 = 0.0 0.0 + x = -1.118033989 + -1.5 x = -1.118033989 + -1.5 Combine like terms: -1.118033989 + -1.5 = -2.618033989 x = -2.618033989 Simplifying x = -2.618033989

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-0.381966011, -2.618033989}

Solution

x = {-0.381966011, -2.618033989}

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