7x^2-28x+15=0

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Solution for 7x^2-28x+15=0 equation:


Simplifying
7x2 + -28x + 15 = 0

Reorder the terms:
15 + -28x + 7x2 = 0

Solving
15 + -28x + 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 + -4x + x2 = 0

Move the constant term to the right:

Add '-2.142857143' to each side of the equation.
2.142857143 + -4x + -2.142857143 + x2 = 0 + -2.142857143

Reorder the terms:
2.142857143 + -2.142857143 + -4x + x2 = 0 + -2.142857143

Combine like terms: 2.142857143 + -2.142857143 = 0.000000000
0.000000000 + -4x + x2 = 0 + -2.142857143
-4x + x2 = 0 + -2.142857143

Combine like terms: 0 + -2.142857143 = -2.142857143
-4x + x2 = -2.142857143

The x term is -4x.  Take half its coefficient (-2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
-4x + 4 + x2 = -2.142857143 + 4

Reorder the terms:
4 + -4x + x2 = -2.142857143 + 4

Combine like terms: -2.142857143 + 4 = 1.857142857
4 + -4x + x2 = 1.857142857

Factor a perfect square on the left side:
(x + -2)(x + -2) = 1.857142857

Calculate the square root of the right side: 1.362770288

Break this problem into two subproblems by setting 
(x + -2) equal to 1.362770288 and -1.362770288.

Subproblem 1

x + -2 = 1.362770288 Simplifying x + -2 = 1.362770288 Reorder the terms: -2 + x = 1.362770288 Solving -2 + x = 1.362770288 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + x = 1.362770288 + 2 Combine like terms: -2 + 2 = 0 0 + x = 1.362770288 + 2 x = 1.362770288 + 2 Combine like terms: 1.362770288 + 2 = 3.362770288 x = 3.362770288 Simplifying x = 3.362770288

Subproblem 2

x + -2 = -1.362770288 Simplifying x + -2 = -1.362770288 Reorder the terms: -2 + x = -1.362770288 Solving -2 + x = -1.362770288 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2' to each side of the equation. -2 + 2 + x = -1.362770288 + 2 Combine like terms: -2 + 2 = 0 0 + x = -1.362770288 + 2 x = -1.362770288 + 2 Combine like terms: -1.362770288 + 2 = 0.637229712 x = 0.637229712 Simplifying x = 0.637229712

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.362770288, 0.637229712}

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