9x^2+11x-18=0

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Solution for 9x^2+11x-18=0 equation:


Simplifying
9x2 + 11x + -18 = 0

Reorder the terms:
-18 + 11x + 9x2 = 0

Solving
-18 + 11x + 9x2 = 0

Solving for variable 'x'.

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

Divide each side by '9'.
-2 + 1.222222222x + x2 = 0

Move the constant term to the right:

Add '2' to each side of the equation.
-2 + 1.222222222x + 2 + x2 = 0 + 2

Reorder the terms:
-2 + 2 + 1.222222222x + x2 = 0 + 2

Combine like terms: -2 + 2 = 0
0 + 1.222222222x + x2 = 0 + 2
1.222222222x + x2 = 0 + 2

Combine like terms: 0 + 2 = 2
1.222222222x + x2 = 2

The x term is 1.222222222x.  Take half its coefficient (0.611111111).
Square it (0.3734567900) and add it to both sides.

Add '0.3734567900' to each side of the equation.
1.222222222x + 0.3734567900 + x2 = 2 + 0.3734567900

Reorder the terms:
0.3734567900 + 1.222222222x + x2 = 2 + 0.3734567900

Combine like terms: 2 + 0.3734567900 = 2.37345679
0.3734567900 + 1.222222222x + x2 = 2.37345679

Factor a perfect square on the left side:
(x + 0.611111111)(x + 0.611111111) = 2.37345679

Calculate the square root of the right side: 1.540602736

Break this problem into two subproblems by setting 
(x + 0.611111111) equal to 1.540602736 and -1.540602736.

Subproblem 1

x + 0.611111111 = 1.540602736 Simplifying x + 0.611111111 = 1.540602736 Reorder the terms: 0.611111111 + x = 1.540602736 Solving 0.611111111 + x = 1.540602736 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.611111111' to each side of the equation. 0.611111111 + -0.611111111 + x = 1.540602736 + -0.611111111 Combine like terms: 0.611111111 + -0.611111111 = 0.000000000 0.000000000 + x = 1.540602736 + -0.611111111 x = 1.540602736 + -0.611111111 Combine like terms: 1.540602736 + -0.611111111 = 0.929491625 x = 0.929491625 Simplifying x = 0.929491625

Subproblem 2

x + 0.611111111 = -1.540602736 Simplifying x + 0.611111111 = -1.540602736 Reorder the terms: 0.611111111 + x = -1.540602736 Solving 0.611111111 + x = -1.540602736 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.611111111' to each side of the equation. 0.611111111 + -0.611111111 + x = -1.540602736 + -0.611111111 Combine like terms: 0.611111111 + -0.611111111 = 0.000000000 0.000000000 + x = -1.540602736 + -0.611111111 x = -1.540602736 + -0.611111111 Combine like terms: -1.540602736 + -0.611111111 = -2.151713847 x = -2.151713847 Simplifying x = -2.151713847

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.929491625, -2.151713847}

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