x^2+21x-107=0

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Solution for x^2+21x-107=0 equation:


Simplifying
x2 + 21x + -107 = 0

Reorder the terms:
-107 + 21x + x2 = 0

Solving
-107 + 21x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '107' to each side of the equation.
-107 + 21x + 107 + x2 = 0 + 107

Reorder the terms:
-107 + 107 + 21x + x2 = 0 + 107

Combine like terms: -107 + 107 = 0
0 + 21x + x2 = 0 + 107
21x + x2 = 0 + 107

Combine like terms: 0 + 107 = 107
21x + x2 = 107

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 = 107 + 110.25

Reorder the terms:
110.25 + 21x + x2 = 107 + 110.25

Combine like terms: 107 + 110.25 = 217.25
110.25 + 21x + x2 = 217.25

Factor a perfect square on the left side:
(x + 10.5)(x + 10.5) = 217.25

Calculate the square root of the right side: 14.739402973

Break this problem into two subproblems by setting 
(x + 10.5) equal to 14.739402973 and -14.739402973.

Subproblem 1

x + 10.5 = 14.739402973 Simplifying x + 10.5 = 14.739402973 Reorder the terms: 10.5 + x = 14.739402973 Solving 10.5 + x = 14.739402973 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 = 14.739402973 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = 14.739402973 + -10.5 x = 14.739402973 + -10.5 Combine like terms: 14.739402973 + -10.5 = 4.239402973 x = 4.239402973 Simplifying x = 4.239402973

Subproblem 2

x + 10.5 = -14.739402973 Simplifying x + 10.5 = -14.739402973 Reorder the terms: 10.5 + x = -14.739402973 Solving 10.5 + x = -14.739402973 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 = -14.739402973 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = -14.739402973 + -10.5 x = -14.739402973 + -10.5 Combine like terms: -14.739402973 + -10.5 = -25.239402973 x = -25.239402973 Simplifying x = -25.239402973

Solution

The solution to the problem is based on the solutions from the subproblems. x = {4.239402973, -25.239402973}

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