x^2+21x+108=2

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Solution for x^2+21x+108=2 equation:


Simplifying
x2 + 21x + 108 = 2

Reorder the terms:
108 + 21x + x2 = 2

Solving
108 + 21x + x2 = 2

Solving for variable 'x'.

Reorder the terms:
108 + -2 + 21x + x2 = 2 + -2

Combine like terms: 108 + -2 = 106
106 + 21x + x2 = 2 + -2

Combine like terms: 2 + -2 = 0
106 + 21x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-106' to each side of the equation.
106 + 21x + -106 + x2 = 0 + -106

Reorder the terms:
106 + -106 + 21x + x2 = 0 + -106

Combine like terms: 106 + -106 = 0
0 + 21x + x2 = 0 + -106
21x + x2 = 0 + -106

Combine like terms: 0 + -106 = -106
21x + x2 = -106

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 = -106 + 110.25

Reorder the terms:
110.25 + 21x + x2 = -106 + 110.25

Combine like terms: -106 + 110.25 = 4.25
110.25 + 21x + x2 = 4.25

Factor a perfect square on the left side:
(x + 10.5)(x + 10.5) = 4.25

Calculate the square root of the right side: 2.061552813

Break this problem into two subproblems by setting 
(x + 10.5) equal to 2.061552813 and -2.061552813.

Subproblem 1

x + 10.5 = 2.061552813 Simplifying x + 10.5 = 2.061552813 Reorder the terms: 10.5 + x = 2.061552813 Solving 10.5 + x = 2.061552813 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 = 2.061552813 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = 2.061552813 + -10.5 x = 2.061552813 + -10.5 Combine like terms: 2.061552813 + -10.5 = -8.438447187 x = -8.438447187 Simplifying x = -8.438447187

Subproblem 2

x + 10.5 = -2.061552813 Simplifying x + 10.5 = -2.061552813 Reorder the terms: 10.5 + x = -2.061552813 Solving 10.5 + x = -2.061552813 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 = -2.061552813 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = -2.061552813 + -10.5 x = -2.061552813 + -10.5 Combine like terms: -2.061552813 + -10.5 = -12.561552813 x = -12.561552813 Simplifying x = -12.561552813

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-8.438447187, -12.561552813}

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