7x^2-16x-9=0

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Solution for 7x^2-16x-9=0 equation:


Simplifying
7x2 + -16x + -9 = 0

Reorder the terms:
-9 + -16x + 7x2 = 0

Solving
-9 + -16x + 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'.
-1.285714286 + -2.285714286x + x2 = 0

Move the constant term to the right:

Add '1.285714286' to each side of the equation.
-1.285714286 + -2.285714286x + 1.285714286 + x2 = 0 + 1.285714286

Reorder the terms:
-1.285714286 + 1.285714286 + -2.285714286x + x2 = 0 + 1.285714286

Combine like terms: -1.285714286 + 1.285714286 = 0.000000000
0.000000000 + -2.285714286x + x2 = 0 + 1.285714286
-2.285714286x + x2 = 0 + 1.285714286

Combine like terms: 0 + 1.285714286 = 1.285714286
-2.285714286x + x2 = 1.285714286

The x term is -2.285714286x.  Take half its coefficient (-1.142857143).
Square it (1.306122449) and add it to both sides.

Add '1.306122449' to each side of the equation.
-2.285714286x + 1.306122449 + x2 = 1.285714286 + 1.306122449

Reorder the terms:
1.306122449 + -2.285714286x + x2 = 1.285714286 + 1.306122449

Combine like terms: 1.285714286 + 1.306122449 = 2.591836735
1.306122449 + -2.285714286x + x2 = 2.591836735

Factor a perfect square on the left side:
(x + -1.142857143)(x + -1.142857143) = 2.591836735

Calculate the square root of the right side: 1.609918239

Break this problem into two subproblems by setting 
(x + -1.142857143) equal to 1.609918239 and -1.609918239.

Subproblem 1

x + -1.142857143 = 1.609918239 Simplifying x + -1.142857143 = 1.609918239 Reorder the terms: -1.142857143 + x = 1.609918239 Solving -1.142857143 + x = 1.609918239 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.142857143' to each side of the equation. -1.142857143 + 1.142857143 + x = 1.609918239 + 1.142857143 Combine like terms: -1.142857143 + 1.142857143 = 0.000000000 0.000000000 + x = 1.609918239 + 1.142857143 x = 1.609918239 + 1.142857143 Combine like terms: 1.609918239 + 1.142857143 = 2.752775382 x = 2.752775382 Simplifying x = 2.752775382

Subproblem 2

x + -1.142857143 = -1.609918239 Simplifying x + -1.142857143 = -1.609918239 Reorder the terms: -1.142857143 + x = -1.609918239 Solving -1.142857143 + x = -1.609918239 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.142857143' to each side of the equation. -1.142857143 + 1.142857143 + x = -1.609918239 + 1.142857143 Combine like terms: -1.142857143 + 1.142857143 = 0.000000000 0.000000000 + x = -1.609918239 + 1.142857143 x = -1.609918239 + 1.142857143 Combine like terms: -1.609918239 + 1.142857143 = -0.467061096 x = -0.467061096 Simplifying x = -0.467061096

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.752775382, -0.467061096}

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