3x^2=9-x

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Solution for 3x^2=9-x equation:


Simplifying
3x2 = 9 + -1x

Solving
3x2 = 9 + -1x

Solving for variable 'x'.

Reorder the terms:
-9 + x + 3x2 = 9 + -1x + -9 + x

Reorder the terms:
-9 + x + 3x2 = 9 + -9 + -1x + x

Combine like terms: 9 + -9 = 0
-9 + x + 3x2 = 0 + -1x + x
-9 + x + 3x2 = -1x + x

Combine like terms: -1x + x = 0
-9 + x + 3x2 = 0

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

Divide each side by '3'.
-3 + 0.3333333333x + x2 = 0

Move the constant term to the right:

Add '3' to each side of the equation.
-3 + 0.3333333333x + 3 + x2 = 0 + 3

Reorder the terms:
-3 + 3 + 0.3333333333x + x2 = 0 + 3

Combine like terms: -3 + 3 = 0
0 + 0.3333333333x + x2 = 0 + 3
0.3333333333x + x2 = 0 + 3

Combine like terms: 0 + 3 = 3
0.3333333333x + x2 = 3

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

Add '0.25' to each side of the equation.
0.3333333333x + 0.25 + x2 = 3 + 0.25

Reorder the terms:
0.25 + 0.3333333333x + x2 = 3 + 0.25

Combine like terms: 3 + 0.25 = 3.25
0.25 + 0.3333333333x + x2 = 3.25

Factor a perfect square on the left side:
(x + 0.5)(x + 0.5) = 3.25

Calculate the square root of the right side: 1.802775638

Break this problem into two subproblems by setting 
(x + 0.5) equal to 1.802775638 and -1.802775638.

Subproblem 1

x + 0.5 = 1.802775638 Simplifying x + 0.5 = 1.802775638 Reorder the terms: 0.5 + x = 1.802775638 Solving 0.5 + x = 1.802775638 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5' to each side of the equation. 0.5 + -0.5 + x = 1.802775638 + -0.5 Combine like terms: 0.5 + -0.5 = 0.0 0.0 + x = 1.802775638 + -0.5 x = 1.802775638 + -0.5 Combine like terms: 1.802775638 + -0.5 = 1.302775638 x = 1.302775638 Simplifying x = 1.302775638

Subproblem 2

x + 0.5 = -1.802775638 Simplifying x + 0.5 = -1.802775638 Reorder the terms: 0.5 + x = -1.802775638 Solving 0.5 + x = -1.802775638 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5' to each side of the equation. 0.5 + -0.5 + x = -1.802775638 + -0.5 Combine like terms: 0.5 + -0.5 = 0.0 0.0 + x = -1.802775638 + -0.5 x = -1.802775638 + -0.5 Combine like terms: -1.802775638 + -0.5 = -2.302775638 x = -2.302775638 Simplifying x = -2.302775638

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.302775638, -2.302775638}

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