18x^2+9x-4=0

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Solution for 18x^2+9x-4=0 equation:


Simplifying
18x2 + 9x + -4 = 0

Reorder the terms:
-4 + 9x + 18x2 = 0

Solving
-4 + 9x + 18x2 = 0

Solving for variable 'x'.

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

Divide each side by '18'.
-0.2222222222 + 0.5x + x2 = 0

Move the constant term to the right:

Add '0.2222222222' to each side of the equation.
-0.2222222222 + 0.5x + 0.2222222222 + x2 = 0 + 0.2222222222

Reorder the terms:
-0.2222222222 + 0.2222222222 + 0.5x + x2 = 0 + 0.2222222222

Combine like terms: -0.2222222222 + 0.2222222222 = 0.0000000000
0.0000000000 + 0.5x + x2 = 0 + 0.2222222222
0.5x + x2 = 0 + 0.2222222222

Combine like terms: 0 + 0.2222222222 = 0.2222222222
0.5x + x2 = 0.2222222222

The x term is 0.5x.  Take half its coefficient (0.25).
Square it (0.0625) and add it to both sides.

Add '0.0625' to each side of the equation.
0.5x + 0.0625 + x2 = 0.2222222222 + 0.0625

Reorder the terms:
0.0625 + 0.5x + x2 = 0.2222222222 + 0.0625

Combine like terms: 0.2222222222 + 0.0625 = 0.2847222222
0.0625 + 0.5x + x2 = 0.2847222222

Factor a perfect square on the left side:
(x + 0.25)(x + 0.25) = 0.2847222222

Calculate the square root of the right side: 0.533593686

Break this problem into two subproblems by setting 
(x + 0.25) equal to 0.533593686 and -0.533593686.

Subproblem 1

x + 0.25 = 0.533593686 Simplifying x + 0.25 = 0.533593686 Reorder the terms: 0.25 + x = 0.533593686 Solving 0.25 + x = 0.533593686 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.25' to each side of the equation. 0.25 + -0.25 + x = 0.533593686 + -0.25 Combine like terms: 0.25 + -0.25 = 0.00 0.00 + x = 0.533593686 + -0.25 x = 0.533593686 + -0.25 Combine like terms: 0.533593686 + -0.25 = 0.283593686 x = 0.283593686 Simplifying x = 0.283593686

Subproblem 2

x + 0.25 = -0.533593686 Simplifying x + 0.25 = -0.533593686 Reorder the terms: 0.25 + x = -0.533593686 Solving 0.25 + x = -0.533593686 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.25' to each side of the equation. 0.25 + -0.25 + x = -0.533593686 + -0.25 Combine like terms: 0.25 + -0.25 = 0.00 0.00 + x = -0.533593686 + -0.25 x = -0.533593686 + -0.25 Combine like terms: -0.533593686 + -0.25 = -0.783593686 x = -0.783593686 Simplifying x = -0.783593686

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.283593686, -0.783593686}

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