0=x^2-7x-7

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Solution for 0=x^2-7x-7 equation:


Simplifying
0 = x2 + -7x + -7

Reorder the terms:
0 = -7 + -7x + x2

Solving
0 = -7 + -7x + x2

Solving for variable 'x'.

Combine like terms: 0 + 7 = 7
7 + 7x + -1x2 = -7 + -7x + x2 + 7 + 7x + -1x2

Reorder the terms:
7 + 7x + -1x2 = -7 + 7 + -7x + 7x + x2 + -1x2

Combine like terms: -7 + 7 = 0
7 + 7x + -1x2 = 0 + -7x + 7x + x2 + -1x2
7 + 7x + -1x2 = -7x + 7x + x2 + -1x2

Combine like terms: -7x + 7x = 0
7 + 7x + -1x2 = 0 + x2 + -1x2
7 + 7x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
7 + 7x + -1x2 = 0

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

Divide each side by '-1'.
-7 + -7x + x2 = 0

Move the constant term to the right:

Add '7' to each side of the equation.
-7 + -7x + 7 + x2 = 0 + 7

Reorder the terms:
-7 + 7 + -7x + x2 = 0 + 7

Combine like terms: -7 + 7 = 0
0 + -7x + x2 = 0 + 7
-7x + x2 = 0 + 7

Combine like terms: 0 + 7 = 7
-7x + x2 = 7

The x term is -7x.  Take half its coefficient (-3.5).
Square it (12.25) and add it to both sides.

Add '12.25' to each side of the equation.
-7x + 12.25 + x2 = 7 + 12.25

Reorder the terms:
12.25 + -7x + x2 = 7 + 12.25

Combine like terms: 7 + 12.25 = 19.25
12.25 + -7x + x2 = 19.25

Factor a perfect square on the left side:
(x + -3.5)(x + -3.5) = 19.25

Calculate the square root of the right side: 4.387482194

Break this problem into two subproblems by setting 
(x + -3.5) equal to 4.387482194 and -4.387482194.

Subproblem 1

x + -3.5 = 4.387482194 Simplifying x + -3.5 = 4.387482194 Reorder the terms: -3.5 + x = 4.387482194 Solving -3.5 + x = 4.387482194 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.5' to each side of the equation. -3.5 + 3.5 + x = 4.387482194 + 3.5 Combine like terms: -3.5 + 3.5 = 0.0 0.0 + x = 4.387482194 + 3.5 x = 4.387482194 + 3.5 Combine like terms: 4.387482194 + 3.5 = 7.887482194 x = 7.887482194 Simplifying x = 7.887482194

Subproblem 2

x + -3.5 = -4.387482194 Simplifying x + -3.5 = -4.387482194 Reorder the terms: -3.5 + x = -4.387482194 Solving -3.5 + x = -4.387482194 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.5' to each side of the equation. -3.5 + 3.5 + x = -4.387482194 + 3.5 Combine like terms: -3.5 + 3.5 = 0.0 0.0 + x = -4.387482194 + 3.5 x = -4.387482194 + 3.5 Combine like terms: -4.387482194 + 3.5 = -0.887482194 x = -0.887482194 Simplifying x = -0.887482194

Solution

The solution to the problem is based on the solutions from the subproblems. x = {7.887482194, -0.887482194}

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