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

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


Simplifying
-7x2 + 15x + 15 = 0

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

Solving
15 + 15x + -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 + -2.142857143x + x2 = 0

Move the constant term to the right:

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

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

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

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

The x term is -2.142857143x.  Take half its coefficient (-1.071428572).
Square it (1.147959185) and add it to both sides.

Add '1.147959185' to each side of the equation.
-2.142857143x + 1.147959185 + x2 = 2.142857143 + 1.147959185

Reorder the terms:
1.147959185 + -2.142857143x + x2 = 2.142857143 + 1.147959185

Combine like terms: 2.142857143 + 1.147959185 = 3.290816328
1.147959185 + -2.142857143x + x2 = 3.290816328

Factor a perfect square on the left side:
(x + -1.071428572)(x + -1.071428572) = 3.290816328

Calculate the square root of the right side: 1.814060729

Break this problem into two subproblems by setting 
(x + -1.071428572) equal to 1.814060729 and -1.814060729.

Subproblem 1

x + -1.071428572 = 1.814060729 Simplifying x + -1.071428572 = 1.814060729 Reorder the terms: -1.071428572 + x = 1.814060729 Solving -1.071428572 + x = 1.814060729 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.071428572' to each side of the equation. -1.071428572 + 1.071428572 + x = 1.814060729 + 1.071428572 Combine like terms: -1.071428572 + 1.071428572 = 0.000000000 0.000000000 + x = 1.814060729 + 1.071428572 x = 1.814060729 + 1.071428572 Combine like terms: 1.814060729 + 1.071428572 = 2.885489301 x = 2.885489301 Simplifying x = 2.885489301

Subproblem 2

x + -1.071428572 = -1.814060729 Simplifying x + -1.071428572 = -1.814060729 Reorder the terms: -1.071428572 + x = -1.814060729 Solving -1.071428572 + x = -1.814060729 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.071428572' to each side of the equation. -1.071428572 + 1.071428572 + x = -1.814060729 + 1.071428572 Combine like terms: -1.071428572 + 1.071428572 = 0.000000000 0.000000000 + x = -1.814060729 + 1.071428572 x = -1.814060729 + 1.071428572 Combine like terms: -1.814060729 + 1.071428572 = -0.742632157 x = -0.742632157 Simplifying x = -0.742632157

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.885489301, -0.742632157}

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