2x^2-13x-42=0

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Solution for 2x^2-13x-42=0 equation:


Simplifying
2x2 + -13x + -42 = 0

Reorder the terms:
-42 + -13x + 2x2 = 0

Solving
-42 + -13x + 2x2 = 0

Solving for variable 'x'.

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

Divide each side by '2'.
-21 + -6.5x + x2 = 0

Move the constant term to the right:

Add '21' to each side of the equation.
-21 + -6.5x + 21 + x2 = 0 + 21

Reorder the terms:
-21 + 21 + -6.5x + x2 = 0 + 21

Combine like terms: -21 + 21 = 0
0 + -6.5x + x2 = 0 + 21
-6.5x + x2 = 0 + 21

Combine like terms: 0 + 21 = 21
-6.5x + x2 = 21

The x term is -6.5x.  Take half its coefficient (-3.25).
Square it (10.5625) and add it to both sides.

Add '10.5625' to each side of the equation.
-6.5x + 10.5625 + x2 = 21 + 10.5625

Reorder the terms:
10.5625 + -6.5x + x2 = 21 + 10.5625

Combine like terms: 21 + 10.5625 = 31.5625
10.5625 + -6.5x + x2 = 31.5625

Factor a perfect square on the left side:
(x + -3.25)(x + -3.25) = 31.5625

Calculate the square root of the right side: 5.618051264

Break this problem into two subproblems by setting 
(x + -3.25) equal to 5.618051264 and -5.618051264.

Subproblem 1

x + -3.25 = 5.618051264 Simplifying x + -3.25 = 5.618051264 Reorder the terms: -3.25 + x = 5.618051264 Solving -3.25 + x = 5.618051264 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.25' to each side of the equation. -3.25 + 3.25 + x = 5.618051264 + 3.25 Combine like terms: -3.25 + 3.25 = 0.00 0.00 + x = 5.618051264 + 3.25 x = 5.618051264 + 3.25 Combine like terms: 5.618051264 + 3.25 = 8.868051264 x = 8.868051264 Simplifying x = 8.868051264

Subproblem 2

x + -3.25 = -5.618051264 Simplifying x + -3.25 = -5.618051264 Reorder the terms: -3.25 + x = -5.618051264 Solving -3.25 + x = -5.618051264 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3.25' to each side of the equation. -3.25 + 3.25 + x = -5.618051264 + 3.25 Combine like terms: -3.25 + 3.25 = 0.00 0.00 + x = -5.618051264 + 3.25 x = -5.618051264 + 3.25 Combine like terms: -5.618051264 + 3.25 = -2.368051264 x = -2.368051264 Simplifying x = -2.368051264

Solution

The solution to the problem is based on the solutions from the subproblems. x = {8.868051264, -2.368051264}

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