7x^2+2x-15=0

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Solution for 7x^2+2x-15=0 equation:


Simplifying
7x2 + 2x + -15 = 0

Reorder the terms:
-15 + 2x + 7x2 = 0

Solving
-15 + 2x + 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'.
-2.142857143 + 0.2857142857x + x2 = 0

Move the constant term to the right:

Add '2.142857143' to each side of the equation.
-2.142857143 + 0.2857142857x + 2.142857143 + x2 = 0 + 2.142857143

Reorder the terms:
-2.142857143 + 2.142857143 + 0.2857142857x + x2 = 0 + 2.142857143

Combine like terms: -2.142857143 + 2.142857143 = 0.000000000
0.000000000 + 0.2857142857x + x2 = 0 + 2.142857143
0.2857142857x + x2 = 0 + 2.142857143

Combine like terms: 0 + 2.142857143 = 2.142857143
0.2857142857x + x2 = 2.142857143

The x term is 0.2857142857x.  Take half its coefficient (0.1428571429).
Square it (0.02040816328) and add it to both sides.

Add '0.02040816328' to each side of the equation.
0.2857142857x + 0.02040816328 + x2 = 2.142857143 + 0.02040816328

Reorder the terms:
0.02040816328 + 0.2857142857x + x2 = 2.142857143 + 0.02040816328

Combine like terms: 2.142857143 + 0.02040816328 = 2.16326530628
0.02040816328 + 0.2857142857x + x2 = 2.16326530628

Factor a perfect square on the left side:
(x + 0.1428571429)(x + 0.1428571429) = 2.16326530628

Calculate the square root of the right side: 1.470804306

Break this problem into two subproblems by setting 
(x + 0.1428571429) equal to 1.470804306 and -1.470804306.

Subproblem 1

x + 0.1428571429 = 1.470804306 Simplifying x + 0.1428571429 = 1.470804306 Reorder the terms: 0.1428571429 + x = 1.470804306 Solving 0.1428571429 + x = 1.470804306 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.1428571429' to each side of the equation. 0.1428571429 + -0.1428571429 + x = 1.470804306 + -0.1428571429 Combine like terms: 0.1428571429 + -0.1428571429 = 0.0000000000 0.0000000000 + x = 1.470804306 + -0.1428571429 x = 1.470804306 + -0.1428571429 Combine like terms: 1.470804306 + -0.1428571429 = 1.3279471631 x = 1.3279471631 Simplifying x = 1.3279471631

Subproblem 2

x + 0.1428571429 = -1.470804306 Simplifying x + 0.1428571429 = -1.470804306 Reorder the terms: 0.1428571429 + x = -1.470804306 Solving 0.1428571429 + x = -1.470804306 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.1428571429' to each side of the equation. 0.1428571429 + -0.1428571429 + x = -1.470804306 + -0.1428571429 Combine like terms: 0.1428571429 + -0.1428571429 = 0.0000000000 0.0000000000 + x = -1.470804306 + -0.1428571429 x = -1.470804306 + -0.1428571429 Combine like terms: -1.470804306 + -0.1428571429 = -1.6136614489 x = -1.6136614489 Simplifying x = -1.6136614489

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.3279471631, -1.6136614489}

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