9x^2+19x-21=0

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Solution for 9x^2+19x-21=0 equation:


Simplifying
9x2 + 19x + -21 = 0

Reorder the terms:
-21 + 19x + 9x2 = 0

Solving
-21 + 19x + 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'.
-2.333333333 + 2.111111111x + x2 = 0

Move the constant term to the right:

Add '2.333333333' to each side of the equation.
-2.333333333 + 2.111111111x + 2.333333333 + x2 = 0 + 2.333333333

Reorder the terms:
-2.333333333 + 2.333333333 + 2.111111111x + x2 = 0 + 2.333333333

Combine like terms: -2.333333333 + 2.333333333 = 0.000000000
0.000000000 + 2.111111111x + x2 = 0 + 2.333333333
2.111111111x + x2 = 0 + 2.333333333

Combine like terms: 0 + 2.333333333 = 2.333333333
2.111111111x + x2 = 2.333333333

The x term is 2.111111111x.  Take half its coefficient (1.055555556).
Square it (1.114197532) and add it to both sides.

Add '1.114197532' to each side of the equation.
2.111111111x + 1.114197532 + x2 = 2.333333333 + 1.114197532

Reorder the terms:
1.114197532 + 2.111111111x + x2 = 2.333333333 + 1.114197532

Combine like terms: 2.333333333 + 1.114197532 = 3.447530865
1.114197532 + 2.111111111x + x2 = 3.447530865

Factor a perfect square on the left side:
(x + 1.055555556)(x + 1.055555556) = 3.447530865

Calculate the square root of the right side: 1.856752774

Break this problem into two subproblems by setting 
(x + 1.055555556) equal to 1.856752774 and -1.856752774.

Subproblem 1

x + 1.055555556 = 1.856752774 Simplifying x + 1.055555556 = 1.856752774 Reorder the terms: 1.055555556 + x = 1.856752774 Solving 1.055555556 + x = 1.856752774 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.055555556' to each side of the equation. 1.055555556 + -1.055555556 + x = 1.856752774 + -1.055555556 Combine like terms: 1.055555556 + -1.055555556 = 0.000000000 0.000000000 + x = 1.856752774 + -1.055555556 x = 1.856752774 + -1.055555556 Combine like terms: 1.856752774 + -1.055555556 = 0.801197218 x = 0.801197218 Simplifying x = 0.801197218

Subproblem 2

x + 1.055555556 = -1.856752774 Simplifying x + 1.055555556 = -1.856752774 Reorder the terms: 1.055555556 + x = -1.856752774 Solving 1.055555556 + x = -1.856752774 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.055555556' to each side of the equation. 1.055555556 + -1.055555556 + x = -1.856752774 + -1.055555556 Combine like terms: 1.055555556 + -1.055555556 = 0.000000000 0.000000000 + x = -1.856752774 + -1.055555556 x = -1.856752774 + -1.055555556 Combine like terms: -1.856752774 + -1.055555556 = -2.91230833 x = -2.91230833 Simplifying x = -2.91230833

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.801197218, -2.91230833}

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