7x^2-18x-71=0

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Solution for 7x^2-18x-71=0 equation:


Simplifying
7x2 + -18x + -71 = 0

Reorder the terms:
-71 + -18x + 7x2 = 0

Solving
-71 + -18x + 7x2 = 0

Solving for variable 'x'.

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

Divide each side by '7'.
-10.14285714 + -2.571428571x + x2 = 0

Move the constant term to the right:

Add '10.14285714' to each side of the equation.
-10.14285714 + -2.571428571x + 10.14285714 + x2 = 0 + 10.14285714

Reorder the terms:
-10.14285714 + 10.14285714 + -2.571428571x + x2 = 0 + 10.14285714

Combine like terms: -10.14285714 + 10.14285714 = 0.00000000
0.00000000 + -2.571428571x + x2 = 0 + 10.14285714
-2.571428571x + x2 = 0 + 10.14285714

Combine like terms: 0 + 10.14285714 = 10.14285714
-2.571428571x + x2 = 10.14285714

The x term is -2.571428571x.  Take half its coefficient (-1.285714286).
Square it (1.653061225) and add it to both sides.

Add '1.653061225' to each side of the equation.
-2.571428571x + 1.653061225 + x2 = 10.14285714 + 1.653061225

Reorder the terms:
1.653061225 + -2.571428571x + x2 = 10.14285714 + 1.653061225

Combine like terms: 10.14285714 + 1.653061225 = 11.795918365
1.653061225 + -2.571428571x + x2 = 11.795918365

Factor a perfect square on the left side:
(x + -1.285714286)(x + -1.285714286) = 11.795918365

Calculate the square root of the right side: 3.434518651

Break this problem into two subproblems by setting 
(x + -1.285714286) equal to 3.434518651 and -3.434518651.

Subproblem 1

x + -1.285714286 = 3.434518651 Simplifying x + -1.285714286 = 3.434518651 Reorder the terms: -1.285714286 + x = 3.434518651 Solving -1.285714286 + x = 3.434518651 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.285714286' to each side of the equation. -1.285714286 + 1.285714286 + x = 3.434518651 + 1.285714286 Combine like terms: -1.285714286 + 1.285714286 = 0.000000000 0.000000000 + x = 3.434518651 + 1.285714286 x = 3.434518651 + 1.285714286 Combine like terms: 3.434518651 + 1.285714286 = 4.720232937 x = 4.720232937 Simplifying x = 4.720232937

Subproblem 2

x + -1.285714286 = -3.434518651 Simplifying x + -1.285714286 = -3.434518651 Reorder the terms: -1.285714286 + x = -3.434518651 Solving -1.285714286 + x = -3.434518651 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.285714286' to each side of the equation. -1.285714286 + 1.285714286 + x = -3.434518651 + 1.285714286 Combine like terms: -1.285714286 + 1.285714286 = 0.000000000 0.000000000 + x = -3.434518651 + 1.285714286 x = -3.434518651 + 1.285714286 Combine like terms: -3.434518651 + 1.285714286 = -2.148804365 x = -2.148804365 Simplifying x = -2.148804365

Solution

The solution to the problem is based on the solutions from the subproblems. x = {4.720232937, -2.148804365}

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