0=x^2-78x-1911

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Solution for 0=x^2-78x-1911 equation:


Simplifying
0 = x2 + -78x + -1911

Reorder the terms:
0 = -1911 + -78x + x2

Solving
0 = -1911 + -78x + x2

Solving for variable 'x'.

Combine like terms: 0 + 1911 = 1911
1911 + 78x + -1x2 = -1911 + -78x + x2 + 1911 + 78x + -1x2

Reorder the terms:
1911 + 78x + -1x2 = -1911 + 1911 + -78x + 78x + x2 + -1x2

Combine like terms: -1911 + 1911 = 0
1911 + 78x + -1x2 = 0 + -78x + 78x + x2 + -1x2
1911 + 78x + -1x2 = -78x + 78x + x2 + -1x2

Combine like terms: -78x + 78x = 0
1911 + 78x + -1x2 = 0 + x2 + -1x2
1911 + 78x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
1911 + 78x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-1911 + -78x + x2 = 0

Move the constant term to the right:

Add '1911' to each side of the equation.
-1911 + -78x + 1911 + x2 = 0 + 1911

Reorder the terms:
-1911 + 1911 + -78x + x2 = 0 + 1911

Combine like terms: -1911 + 1911 = 0
0 + -78x + x2 = 0 + 1911
-78x + x2 = 0 + 1911

Combine like terms: 0 + 1911 = 1911
-78x + x2 = 1911

The x term is -78x.  Take half its coefficient (-39).
Square it (1521) and add it to both sides.

Add '1521' to each side of the equation.
-78x + 1521 + x2 = 1911 + 1521

Reorder the terms:
1521 + -78x + x2 = 1911 + 1521

Combine like terms: 1911 + 1521 = 3432
1521 + -78x + x2 = 3432

Factor a perfect square on the left side:
(x + -39)(x + -39) = 3432

Calculate the square root of the right side: 58.583274064

Break this problem into two subproblems by setting 
(x + -39) equal to 58.583274064 and -58.583274064.

Subproblem 1

x + -39 = 58.583274064 Simplifying x + -39 = 58.583274064 Reorder the terms: -39 + x = 58.583274064 Solving -39 + x = 58.583274064 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '39' to each side of the equation. -39 + 39 + x = 58.583274064 + 39 Combine like terms: -39 + 39 = 0 0 + x = 58.583274064 + 39 x = 58.583274064 + 39 Combine like terms: 58.583274064 + 39 = 97.583274064 x = 97.583274064 Simplifying x = 97.583274064

Subproblem 2

x + -39 = -58.583274064 Simplifying x + -39 = -58.583274064 Reorder the terms: -39 + x = -58.583274064 Solving -39 + x = -58.583274064 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '39' to each side of the equation. -39 + 39 + x = -58.583274064 + 39 Combine like terms: -39 + 39 = 0 0 + x = -58.583274064 + 39 x = -58.583274064 + 39 Combine like terms: -58.583274064 + 39 = -19.583274064 x = -19.583274064 Simplifying x = -19.583274064

Solution

The solution to the problem is based on the solutions from the subproblems. x = {97.583274064, -19.583274064}

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