13x^2-69x-18=0

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Solution for 13x^2-69x-18=0 equation:


Simplifying
13x2 + -69x + -18 = 0

Reorder the terms:
-18 + -69x + 13x2 = 0

Solving
-18 + -69x + 13x2 = 0

Solving for variable 'x'.

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

Divide each side by '13'.
-1.384615385 + -5.307692308x + x2 = 0

Move the constant term to the right:

Add '1.384615385' to each side of the equation.
-1.384615385 + -5.307692308x + 1.384615385 + x2 = 0 + 1.384615385

Reorder the terms:
-1.384615385 + 1.384615385 + -5.307692308x + x2 = 0 + 1.384615385

Combine like terms: -1.384615385 + 1.384615385 = 0.000000000
0.000000000 + -5.307692308x + x2 = 0 + 1.384615385
-5.307692308x + x2 = 0 + 1.384615385

Combine like terms: 0 + 1.384615385 = 1.384615385
-5.307692308x + x2 = 1.384615385

The x term is -5.307692308x.  Take half its coefficient (-2.653846154).
Square it (7.042899409) and add it to both sides.

Add '7.042899409' to each side of the equation.
-5.307692308x + 7.042899409 + x2 = 1.384615385 + 7.042899409

Reorder the terms:
7.042899409 + -5.307692308x + x2 = 1.384615385 + 7.042899409

Combine like terms: 1.384615385 + 7.042899409 = 8.427514794
7.042899409 + -5.307692308x + x2 = 8.427514794

Factor a perfect square on the left side:
(x + -2.653846154)(x + -2.653846154) = 8.427514794

Calculate the square root of the right side: 2.903018221

Break this problem into two subproblems by setting 
(x + -2.653846154) equal to 2.903018221 and -2.903018221.

Subproblem 1

x + -2.653846154 = 2.903018221 Simplifying x + -2.653846154 = 2.903018221 Reorder the terms: -2.653846154 + x = 2.903018221 Solving -2.653846154 + x = 2.903018221 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.653846154' to each side of the equation. -2.653846154 + 2.653846154 + x = 2.903018221 + 2.653846154 Combine like terms: -2.653846154 + 2.653846154 = 0.000000000 0.000000000 + x = 2.903018221 + 2.653846154 x = 2.903018221 + 2.653846154 Combine like terms: 2.903018221 + 2.653846154 = 5.556864375 x = 5.556864375 Simplifying x = 5.556864375

Subproblem 2

x + -2.653846154 = -2.903018221 Simplifying x + -2.653846154 = -2.903018221 Reorder the terms: -2.653846154 + x = -2.903018221 Solving -2.653846154 + x = -2.903018221 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.653846154' to each side of the equation. -2.653846154 + 2.653846154 + x = -2.903018221 + 2.653846154 Combine like terms: -2.653846154 + 2.653846154 = 0.000000000 0.000000000 + x = -2.903018221 + 2.653846154 x = -2.903018221 + 2.653846154 Combine like terms: -2.903018221 + 2.653846154 = -0.249172067 x = -0.249172067 Simplifying x = -0.249172067

Solution

The solution to the problem is based on the solutions from the subproblems. x = {5.556864375, -0.249172067}

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