-7x^2-5x+15=0

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Solution for -7x^2-5x+15=0 equation:


Simplifying
-7x2 + -5x + 15 = 0

Reorder the terms:
15 + -5x + -7x2 = 0

Solving
15 + -5x + -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 + 0.7142857143x + x2 = 0

Move the constant term to the right:

Add '2.142857143' to each side of the equation.
-2.142857143 + 0.7142857143x + 2.142857143 + x2 = 0 + 2.142857143

Reorder the terms:
-2.142857143 + 2.142857143 + 0.7142857143x + x2 = 0 + 2.142857143

Combine like terms: -2.142857143 + 2.142857143 = 0.000000000
0.000000000 + 0.7142857143x + x2 = 0 + 2.142857143
0.7142857143x + x2 = 0 + 2.142857143

Combine like terms: 0 + 2.142857143 = 2.142857143
0.7142857143x + x2 = 2.142857143

The x term is 0.7142857143x.  Take half its coefficient (0.3571428572).
Square it (0.1275510204) and add it to both sides.

Add '0.1275510204' to each side of the equation.
0.7142857143x + 0.1275510204 + x2 = 2.142857143 + 0.1275510204

Reorder the terms:
0.1275510204 + 0.7142857143x + x2 = 2.142857143 + 0.1275510204

Combine like terms: 2.142857143 + 0.1275510204 = 2.2704081634
0.1275510204 + 0.7142857143x + x2 = 2.2704081634

Factor a perfect square on the left side:
(x + 0.3571428572)(x + 0.3571428572) = 2.2704081634

Calculate the square root of the right side: 1.506787365

Break this problem into two subproblems by setting 
(x + 0.3571428572) equal to 1.506787365 and -1.506787365.

Subproblem 1

x + 0.3571428572 = 1.506787365 Simplifying x + 0.3571428572 = 1.506787365 Reorder the terms: 0.3571428572 + x = 1.506787365 Solving 0.3571428572 + x = 1.506787365 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.3571428572' to each side of the equation. 0.3571428572 + -0.3571428572 + x = 1.506787365 + -0.3571428572 Combine like terms: 0.3571428572 + -0.3571428572 = 0.0000000000 0.0000000000 + x = 1.506787365 + -0.3571428572 x = 1.506787365 + -0.3571428572 Combine like terms: 1.506787365 + -0.3571428572 = 1.1496445078 x = 1.1496445078 Simplifying x = 1.1496445078

Subproblem 2

x + 0.3571428572 = -1.506787365 Simplifying x + 0.3571428572 = -1.506787365 Reorder the terms: 0.3571428572 + x = -1.506787365 Solving 0.3571428572 + x = -1.506787365 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.3571428572' to each side of the equation. 0.3571428572 + -0.3571428572 + x = -1.506787365 + -0.3571428572 Combine like terms: 0.3571428572 + -0.3571428572 = 0.0000000000 0.0000000000 + x = -1.506787365 + -0.3571428572 x = -1.506787365 + -0.3571428572 Combine like terms: -1.506787365 + -0.3571428572 = -1.8639302222 x = -1.8639302222 Simplifying x = -1.8639302222

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.1496445078, -1.8639302222}

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