3x^2-9x=13

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Solution for 3x^2-9x=13 equation:


Simplifying
3x2 + -9x = 13

Reorder the terms:
-9x + 3x2 = 13

Solving
-9x + 3x2 = 13

Solving for variable 'x'.

Reorder the terms:
-13 + -9x + 3x2 = 13 + -13

Combine like terms: 13 + -13 = 0
-13 + -9x + 3x2 = 0

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

Divide each side by '3'.
-4.333333333 + -3x + x2 = 0

Move the constant term to the right:

Add '4.333333333' to each side of the equation.
-4.333333333 + -3x + 4.333333333 + x2 = 0 + 4.333333333

Reorder the terms:
-4.333333333 + 4.333333333 + -3x + x2 = 0 + 4.333333333

Combine like terms: -4.333333333 + 4.333333333 = 0.000000000
0.000000000 + -3x + x2 = 0 + 4.333333333
-3x + x2 = 0 + 4.333333333

Combine like terms: 0 + 4.333333333 = 4.333333333
-3x + x2 = 4.333333333

The x term is -3x.  Take half its coefficient (-1.5).
Square it (2.25) and add it to both sides.

Add '2.25' to each side of the equation.
-3x + 2.25 + x2 = 4.333333333 + 2.25

Reorder the terms:
2.25 + -3x + x2 = 4.333333333 + 2.25

Combine like terms: 4.333333333 + 2.25 = 6.583333333
2.25 + -3x + x2 = 6.583333333

Factor a perfect square on the left side:
(x + -1.5)(x + -1.5) = 6.583333333

Calculate the square root of the right side: 2.56580072

Break this problem into two subproblems by setting 
(x + -1.5) equal to 2.56580072 and -2.56580072.

Subproblem 1

x + -1.5 = 2.56580072 Simplifying x + -1.5 = 2.56580072 Reorder the terms: -1.5 + x = 2.56580072 Solving -1.5 + x = 2.56580072 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.5' to each side of the equation. -1.5 + 1.5 + x = 2.56580072 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = 2.56580072 + 1.5 x = 2.56580072 + 1.5 Combine like terms: 2.56580072 + 1.5 = 4.06580072 x = 4.06580072 Simplifying x = 4.06580072

Subproblem 2

x + -1.5 = -2.56580072 Simplifying x + -1.5 = -2.56580072 Reorder the terms: -1.5 + x = -2.56580072 Solving -1.5 + x = -2.56580072 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.5' to each side of the equation. -1.5 + 1.5 + x = -2.56580072 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = -2.56580072 + 1.5 x = -2.56580072 + 1.5 Combine like terms: -2.56580072 + 1.5 = -1.06580072 x = -1.06580072 Simplifying x = -1.06580072

Solution

The solution to the problem is based on the solutions from the subproblems. x = {4.06580072, -1.06580072}

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