(3x-9)x=79

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Solution for (3x-9)x=79 equation:


Simplifying
(3x + -9) * x = 79

Reorder the terms:
(-9 + 3x) * x = 79

Reorder the terms for easier multiplication:
x(-9 + 3x) = 79
(-9 * x + 3x * x) = 79
(-9x + 3x2) = 79

Solving
-9x + 3x2 = 79

Solving for variable 'x'.

Reorder the terms:
-79 + -9x + 3x2 = 79 + -79

Combine like terms: 79 + -79 = 0
-79 + -9x + 3x2 = 0

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

Divide each side by '3'.
-26.33333333 + -3x + x2 = 0

Move the constant term to the right:

Add '26.33333333' to each side of the equation.
-26.33333333 + -3x + 26.33333333 + x2 = 0 + 26.33333333

Reorder the terms:
-26.33333333 + 26.33333333 + -3x + x2 = 0 + 26.33333333

Combine like terms: -26.33333333 + 26.33333333 = 0.00000000
0.00000000 + -3x + x2 = 0 + 26.33333333
-3x + x2 = 0 + 26.33333333

Combine like terms: 0 + 26.33333333 = 26.33333333
-3x + x2 = 26.33333333

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 = 26.33333333 + 2.25

Reorder the terms:
2.25 + -3x + x2 = 26.33333333 + 2.25

Combine like terms: 26.33333333 + 2.25 = 28.58333333
2.25 + -3x + x2 = 28.58333333

Factor a perfect square on the left side:
(x + -1.5)(x + -1.5) = 28.58333333

Calculate the square root of the right side: 5.34633831

Break this problem into two subproblems by setting 
(x + -1.5) equal to 5.34633831 and -5.34633831.

Subproblem 1

x + -1.5 = 5.34633831 Simplifying x + -1.5 = 5.34633831 Reorder the terms: -1.5 + x = 5.34633831 Solving -1.5 + x = 5.34633831 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 = 5.34633831 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = 5.34633831 + 1.5 x = 5.34633831 + 1.5 Combine like terms: 5.34633831 + 1.5 = 6.84633831 x = 6.84633831 Simplifying x = 6.84633831

Subproblem 2

x + -1.5 = -5.34633831 Simplifying x + -1.5 = -5.34633831 Reorder the terms: -1.5 + x = -5.34633831 Solving -1.5 + x = -5.34633831 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 = -5.34633831 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = -5.34633831 + 1.5 x = -5.34633831 + 1.5 Combine like terms: -5.34633831 + 1.5 = -3.84633831 x = -3.84633831 Simplifying x = -3.84633831

Solution

The solution to the problem is based on the solutions from the subproblems. x = {6.84633831, -3.84633831}

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