7x^2-17x-42=0

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Solution for 7x^2-17x-42=0 equation:


Simplifying
7x2 + -17x + -42 = 0

Reorder the terms:
-42 + -17x + 7x2 = 0

Solving
-42 + -17x + 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'.
-6 + -2.428571429x + x2 = 0

Move the constant term to the right:

Add '6' to each side of the equation.
-6 + -2.428571429x + 6 + x2 = 0 + 6

Reorder the terms:
-6 + 6 + -2.428571429x + x2 = 0 + 6

Combine like terms: -6 + 6 = 0
0 + -2.428571429x + x2 = 0 + 6
-2.428571429x + x2 = 0 + 6

Combine like terms: 0 + 6 = 6
-2.428571429x + x2 = 6

The x term is -2.428571429x.  Take half its coefficient (-1.214285715).
Square it (1.474489798) and add it to both sides.

Add '1.474489798' to each side of the equation.
-2.428571429x + 1.474489798 + x2 = 6 + 1.474489798

Reorder the terms:
1.474489798 + -2.428571429x + x2 = 6 + 1.474489798

Combine like terms: 6 + 1.474489798 = 7.474489798
1.474489798 + -2.428571429x + x2 = 7.474489798

Factor a perfect square on the left side:
(x + -1.214285715)(x + -1.214285715) = 7.474489798

Calculate the square root of the right side: 2.733951316

Break this problem into two subproblems by setting 
(x + -1.214285715) equal to 2.733951316 and -2.733951316.

Subproblem 1

x + -1.214285715 = 2.733951316 Simplifying x + -1.214285715 = 2.733951316 Reorder the terms: -1.214285715 + x = 2.733951316 Solving -1.214285715 + x = 2.733951316 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.214285715' to each side of the equation. -1.214285715 + 1.214285715 + x = 2.733951316 + 1.214285715 Combine like terms: -1.214285715 + 1.214285715 = 0.000000000 0.000000000 + x = 2.733951316 + 1.214285715 x = 2.733951316 + 1.214285715 Combine like terms: 2.733951316 + 1.214285715 = 3.948237031 x = 3.948237031 Simplifying x = 3.948237031

Subproblem 2

x + -1.214285715 = -2.733951316 Simplifying x + -1.214285715 = -2.733951316 Reorder the terms: -1.214285715 + x = -2.733951316 Solving -1.214285715 + x = -2.733951316 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.214285715' to each side of the equation. -1.214285715 + 1.214285715 + x = -2.733951316 + 1.214285715 Combine like terms: -1.214285715 + 1.214285715 = 0.000000000 0.000000000 + x = -2.733951316 + 1.214285715 x = -2.733951316 + 1.214285715 Combine like terms: -2.733951316 + 1.214285715 = -1.519665601 x = -1.519665601 Simplifying x = -1.519665601

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.948237031, -1.519665601}

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