28x^2+7x-9=0

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Solution for 28x^2+7x-9=0 equation:


Simplifying
28x2 + 7x + -9 = 0

Reorder the terms:
-9 + 7x + 28x2 = 0

Solving
-9 + 7x + 28x2 = 0

Solving for variable 'x'.

Begin completing the square.  Divide all terms by
28 the coefficient of the squared term: 

Divide each side by '28'.
-0.3214285714 + 0.25x + x2 = 0

Move the constant term to the right:

Add '0.3214285714' to each side of the equation.
-0.3214285714 + 0.25x + 0.3214285714 + x2 = 0 + 0.3214285714

Reorder the terms:
-0.3214285714 + 0.3214285714 + 0.25x + x2 = 0 + 0.3214285714

Combine like terms: -0.3214285714 + 0.3214285714 = 0.0000000000
0.0000000000 + 0.25x + x2 = 0 + 0.3214285714
0.25x + x2 = 0 + 0.3214285714

Combine like terms: 0 + 0.3214285714 = 0.3214285714
0.25x + x2 = 0.3214285714

The x term is 0.25x.  Take half its coefficient (0.125).
Square it (0.015625) and add it to both sides.

Add '0.015625' to each side of the equation.
0.25x + 0.015625 + x2 = 0.3214285714 + 0.015625

Reorder the terms:
0.015625 + 0.25x + x2 = 0.3214285714 + 0.015625

Combine like terms: 0.3214285714 + 0.015625 = 0.3370535714
0.015625 + 0.25x + x2 = 0.3370535714

Factor a perfect square on the left side:
(x + 0.125)(x + 0.125) = 0.3370535714

Calculate the square root of the right side: 0.58056315

Break this problem into two subproblems by setting 
(x + 0.125) equal to 0.58056315 and -0.58056315.

Subproblem 1

x + 0.125 = 0.58056315 Simplifying x + 0.125 = 0.58056315 Reorder the terms: 0.125 + x = 0.58056315 Solving 0.125 + x = 0.58056315 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.125' to each side of the equation. 0.125 + -0.125 + x = 0.58056315 + -0.125 Combine like terms: 0.125 + -0.125 = 0.000 0.000 + x = 0.58056315 + -0.125 x = 0.58056315 + -0.125 Combine like terms: 0.58056315 + -0.125 = 0.45556315 x = 0.45556315 Simplifying x = 0.45556315

Subproblem 2

x + 0.125 = -0.58056315 Simplifying x + 0.125 = -0.58056315 Reorder the terms: 0.125 + x = -0.58056315 Solving 0.125 + x = -0.58056315 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.125' to each side of the equation. 0.125 + -0.125 + x = -0.58056315 + -0.125 Combine like terms: 0.125 + -0.125 = 0.000 0.000 + x = -0.58056315 + -0.125 x = -0.58056315 + -0.125 Combine like terms: -0.58056315 + -0.125 = -0.70556315 x = -0.70556315 Simplifying x = -0.70556315

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.45556315, -0.70556315}

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