x^2+14x+21=0

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Solution for x^2+14x+21=0 equation:


Simplifying
x2 + 14x + 21 = 0

Reorder the terms:
21 + 14x + x2 = 0

Solving
21 + 14x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-21' to each side of the equation.
21 + 14x + -21 + x2 = 0 + -21

Reorder the terms:
21 + -21 + 14x + x2 = 0 + -21

Combine like terms: 21 + -21 = 0
0 + 14x + x2 = 0 + -21
14x + x2 = 0 + -21

Combine like terms: 0 + -21 = -21
14x + x2 = -21

The x term is 14x.  Take half its coefficient (7).
Square it (49) and add it to both sides.

Add '49' to each side of the equation.
14x + 49 + x2 = -21 + 49

Reorder the terms:
49 + 14x + x2 = -21 + 49

Combine like terms: -21 + 49 = 28
49 + 14x + x2 = 28

Factor a perfect square on the left side:
(x + 7)(x + 7) = 28

Calculate the square root of the right side: 5.291502622

Break this problem into two subproblems by setting 
(x + 7) equal to 5.291502622 and -5.291502622.

Subproblem 1

x + 7 = 5.291502622 Simplifying x + 7 = 5.291502622 Reorder the terms: 7 + x = 5.291502622 Solving 7 + x = 5.291502622 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-7' to each side of the equation. 7 + -7 + x = 5.291502622 + -7 Combine like terms: 7 + -7 = 0 0 + x = 5.291502622 + -7 x = 5.291502622 + -7 Combine like terms: 5.291502622 + -7 = -1.708497378 x = -1.708497378 Simplifying x = -1.708497378

Subproblem 2

x + 7 = -5.291502622 Simplifying x + 7 = -5.291502622 Reorder the terms: 7 + x = -5.291502622 Solving 7 + x = -5.291502622 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-7' to each side of the equation. 7 + -7 + x = -5.291502622 + -7 Combine like terms: 7 + -7 = 0 0 + x = -5.291502622 + -7 x = -5.291502622 + -7 Combine like terms: -5.291502622 + -7 = -12.291502622 x = -12.291502622 Simplifying x = -12.291502622

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-1.708497378, -12.291502622}

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