2x^2-21x-2=0

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


Simplifying
2x2 + -21x + -2 = 0

Reorder the terms:
-2 + -21x + 2x2 = 0

Solving
-2 + -21x + 2x2 = 0

Solving for variable 'x'.

Begin completing the square.  Divide all terms by
2 the coefficient of the squared term: 

Divide each side by '2'.
-1 + -10.5x + x2 = 0

Move the constant term to the right:

Add '1' to each side of the equation.
-1 + -10.5x + 1 + x2 = 0 + 1

Reorder the terms:
-1 + 1 + -10.5x + x2 = 0 + 1

Combine like terms: -1 + 1 = 0
0 + -10.5x + x2 = 0 + 1
-10.5x + x2 = 0 + 1

Combine like terms: 0 + 1 = 1
-10.5x + x2 = 1

The x term is -10.5x.  Take half its coefficient (-5.25).
Square it (27.5625) and add it to both sides.

Add '27.5625' to each side of the equation.
-10.5x + 27.5625 + x2 = 1 + 27.5625

Reorder the terms:
27.5625 + -10.5x + x2 = 1 + 27.5625

Combine like terms: 1 + 27.5625 = 28.5625
27.5625 + -10.5x + x2 = 28.5625

Factor a perfect square on the left side:
(x + -5.25)(x + -5.25) = 28.5625

Calculate the square root of the right side: 5.344389582

Break this problem into two subproblems by setting 
(x + -5.25) equal to 5.344389582 and -5.344389582.

Subproblem 1

x + -5.25 = 5.344389582 Simplifying x + -5.25 = 5.344389582 Reorder the terms: -5.25 + x = 5.344389582 Solving -5.25 + x = 5.344389582 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '5.25' to each side of the equation. -5.25 + 5.25 + x = 5.344389582 + 5.25 Combine like terms: -5.25 + 5.25 = 0.00 0.00 + x = 5.344389582 + 5.25 x = 5.344389582 + 5.25 Combine like terms: 5.344389582 + 5.25 = 10.594389582 x = 10.594389582 Simplifying x = 10.594389582

Subproblem 2

x + -5.25 = -5.344389582 Simplifying x + -5.25 = -5.344389582 Reorder the terms: -5.25 + x = -5.344389582 Solving -5.25 + x = -5.344389582 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '5.25' to each side of the equation. -5.25 + 5.25 + x = -5.344389582 + 5.25 Combine like terms: -5.25 + 5.25 = 0.00 0.00 + x = -5.344389582 + 5.25 x = -5.344389582 + 5.25 Combine like terms: -5.344389582 + 5.25 = -0.094389582 x = -0.094389582 Simplifying x = -0.094389582

Solution

The solution to the problem is based on the solutions from the subproblems. x = {10.594389582, -0.094389582}

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