x^2+21x+49=0

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Solution for x^2+21x+49=0 equation:


Simplifying
x2 + 21x + 49 = 0

Reorder the terms:
49 + 21x + x2 = 0

Solving
49 + 21x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-49' to each side of the equation.
49 + 21x + -49 + x2 = 0 + -49

Reorder the terms:
49 + -49 + 21x + x2 = 0 + -49

Combine like terms: 49 + -49 = 0
0 + 21x + x2 = 0 + -49
21x + x2 = 0 + -49

Combine like terms: 0 + -49 = -49
21x + x2 = -49

The x term is 21x.  Take half its coefficient (10.5).
Square it (110.25) and add it to both sides.

Add '110.25' to each side of the equation.
21x + 110.25 + x2 = -49 + 110.25

Reorder the terms:
110.25 + 21x + x2 = -49 + 110.25

Combine like terms: -49 + 110.25 = 61.25
110.25 + 21x + x2 = 61.25

Factor a perfect square on the left side:
(x + 10.5)(x + 10.5) = 61.25

Calculate the square root of the right side: 7.826237921

Break this problem into two subproblems by setting 
(x + 10.5) equal to 7.826237921 and -7.826237921.

Subproblem 1

x + 10.5 = 7.826237921 Simplifying x + 10.5 = 7.826237921 Reorder the terms: 10.5 + x = 7.826237921 Solving 10.5 + x = 7.826237921 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10.5' to each side of the equation. 10.5 + -10.5 + x = 7.826237921 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = 7.826237921 + -10.5 x = 7.826237921 + -10.5 Combine like terms: 7.826237921 + -10.5 = -2.673762079 x = -2.673762079 Simplifying x = -2.673762079

Subproblem 2

x + 10.5 = -7.826237921 Simplifying x + 10.5 = -7.826237921 Reorder the terms: 10.5 + x = -7.826237921 Solving 10.5 + x = -7.826237921 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10.5' to each side of the equation. 10.5 + -10.5 + x = -7.826237921 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = -7.826237921 + -10.5 x = -7.826237921 + -10.5 Combine like terms: -7.826237921 + -10.5 = -18.326237921 x = -18.326237921 Simplifying x = -18.326237921

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-2.673762079, -18.326237921}

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