9x^2+20x-1=0

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Solution for 9x^2+20x-1=0 equation:


Simplifying
9x2 + 20x + -1 = 0

Reorder the terms:
-1 + 20x + 9x2 = 0

Solving
-1 + 20x + 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'.
-0.1111111111 + 2.222222222x + x2 = 0

Move the constant term to the right:

Add '0.1111111111' to each side of the equation.
-0.1111111111 + 2.222222222x + 0.1111111111 + x2 = 0 + 0.1111111111

Reorder the terms:
-0.1111111111 + 0.1111111111 + 2.222222222x + x2 = 0 + 0.1111111111

Combine like terms: -0.1111111111 + 0.1111111111 = 0.0000000000
0.0000000000 + 2.222222222x + x2 = 0 + 0.1111111111
2.222222222x + x2 = 0 + 0.1111111111

Combine like terms: 0 + 0.1111111111 = 0.1111111111
2.222222222x + x2 = 0.1111111111

The x term is 2.222222222x.  Take half its coefficient (1.111111111).
Square it (1.234567901) and add it to both sides.

Add '1.234567901' to each side of the equation.
2.222222222x + 1.234567901 + x2 = 0.1111111111 + 1.234567901

Reorder the terms:
1.234567901 + 2.222222222x + x2 = 0.1111111111 + 1.234567901

Combine like terms: 0.1111111111 + 1.234567901 = 1.3456790121
1.234567901 + 2.222222222x + x2 = 1.3456790121

Factor a perfect square on the left side:
(x + 1.111111111)(x + 1.111111111) = 1.3456790121

Calculate the square root of the right side: 1.160034056

Break this problem into two subproblems by setting 
(x + 1.111111111) equal to 1.160034056 and -1.160034056.

Subproblem 1

x + 1.111111111 = 1.160034056 Simplifying x + 1.111111111 = 1.160034056 Reorder the terms: 1.111111111 + x = 1.160034056 Solving 1.111111111 + x = 1.160034056 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.111111111' to each side of the equation. 1.111111111 + -1.111111111 + x = 1.160034056 + -1.111111111 Combine like terms: 1.111111111 + -1.111111111 = 0.000000000 0.000000000 + x = 1.160034056 + -1.111111111 x = 1.160034056 + -1.111111111 Combine like terms: 1.160034056 + -1.111111111 = 0.048922945 x = 0.048922945 Simplifying x = 0.048922945

Subproblem 2

x + 1.111111111 = -1.160034056 Simplifying x + 1.111111111 = -1.160034056 Reorder the terms: 1.111111111 + x = -1.160034056 Solving 1.111111111 + x = -1.160034056 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.111111111' to each side of the equation. 1.111111111 + -1.111111111 + x = -1.160034056 + -1.111111111 Combine like terms: 1.111111111 + -1.111111111 = 0.000000000 0.000000000 + x = -1.160034056 + -1.111111111 x = -1.160034056 + -1.111111111 Combine like terms: -1.160034056 + -1.111111111 = -2.271145167 x = -2.271145167 Simplifying x = -2.271145167

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.048922945, -2.271145167}

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