x^2-2x-4=42

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Solution for x^2-2x-4=42 equation:


Simplifying
x2 + -2x + -4 = 42

Reorder the terms:
-4 + -2x + x2 = 42

Solving
-4 + -2x + x2 = 42

Solving for variable 'x'.

Reorder the terms:
-4 + -42 + -2x + x2 = 42 + -42

Combine like terms: -4 + -42 = -46
-46 + -2x + x2 = 42 + -42

Combine like terms: 42 + -42 = 0
-46 + -2x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '46' to each side of the equation.
-46 + -2x + 46 + x2 = 0 + 46

Reorder the terms:
-46 + 46 + -2x + x2 = 0 + 46

Combine like terms: -46 + 46 = 0
0 + -2x + x2 = 0 + 46
-2x + x2 = 0 + 46

Combine like terms: 0 + 46 = 46
-2x + x2 = 46

The x term is -2x.  Take half its coefficient (-1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
-2x + 1 + x2 = 46 + 1

Reorder the terms:
1 + -2x + x2 = 46 + 1

Combine like terms: 46 + 1 = 47
1 + -2x + x2 = 47

Factor a perfect square on the left side:
(x + -1)(x + -1) = 47

Calculate the square root of the right side: 6.8556546

Break this problem into two subproblems by setting 
(x + -1) equal to 6.8556546 and -6.8556546.

Subproblem 1

x + -1 = 6.8556546 Simplifying x + -1 = 6.8556546 Reorder the terms: -1 + x = 6.8556546 Solving -1 + x = 6.8556546 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1' to each side of the equation. -1 + 1 + x = 6.8556546 + 1 Combine like terms: -1 + 1 = 0 0 + x = 6.8556546 + 1 x = 6.8556546 + 1 Combine like terms: 6.8556546 + 1 = 7.8556546 x = 7.8556546 Simplifying x = 7.8556546

Subproblem 2

x + -1 = -6.8556546 Simplifying x + -1 = -6.8556546 Reorder the terms: -1 + x = -6.8556546 Solving -1 + x = -6.8556546 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1' to each side of the equation. -1 + 1 + x = -6.8556546 + 1 Combine like terms: -1 + 1 = 0 0 + x = -6.8556546 + 1 x = -6.8556546 + 1 Combine like terms: -6.8556546 + 1 = -5.8556546 x = -5.8556546 Simplifying x = -5.8556546

Solution

The solution to the problem is based on the solutions from the subproblems. x = {7.8556546, -5.8556546}

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