3x^2-9x=8

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Solution for 3x^2-9x=8 equation:


Simplifying
3x2 + -9x = 8

Reorder the terms:
-9x + 3x2 = 8

Solving
-9x + 3x2 = 8

Solving for variable 'x'.

Reorder the terms:
-8 + -9x + 3x2 = 8 + -8

Combine like terms: 8 + -8 = 0
-8 + -9x + 3x2 = 0

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

Divide each side by '3'.
-2.666666667 + -3x + x2 = 0

Move the constant term to the right:

Add '2.666666667' to each side of the equation.
-2.666666667 + -3x + 2.666666667 + x2 = 0 + 2.666666667

Reorder the terms:
-2.666666667 + 2.666666667 + -3x + x2 = 0 + 2.666666667

Combine like terms: -2.666666667 + 2.666666667 = 0.000000000
0.000000000 + -3x + x2 = 0 + 2.666666667
-3x + x2 = 0 + 2.666666667

Combine like terms: 0 + 2.666666667 = 2.666666667
-3x + x2 = 2.666666667

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 = 2.666666667 + 2.25

Reorder the terms:
2.25 + -3x + x2 = 2.666666667 + 2.25

Combine like terms: 2.666666667 + 2.25 = 4.916666667
2.25 + -3x + x2 = 4.916666667

Factor a perfect square on the left side:
(x + -1.5)(x + -1.5) = 4.916666667

Calculate the square root of the right side: 2.217355783

Break this problem into two subproblems by setting 
(x + -1.5) equal to 2.217355783 and -2.217355783.

Subproblem 1

x + -1.5 = 2.217355783 Simplifying x + -1.5 = 2.217355783 Reorder the terms: -1.5 + x = 2.217355783 Solving -1.5 + x = 2.217355783 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 = 2.217355783 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = 2.217355783 + 1.5 x = 2.217355783 + 1.5 Combine like terms: 2.217355783 + 1.5 = 3.717355783 x = 3.717355783 Simplifying x = 3.717355783

Subproblem 2

x + -1.5 = -2.217355783 Simplifying x + -1.5 = -2.217355783 Reorder the terms: -1.5 + x = -2.217355783 Solving -1.5 + x = -2.217355783 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 = -2.217355783 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + x = -2.217355783 + 1.5 x = -2.217355783 + 1.5 Combine like terms: -2.217355783 + 1.5 = -0.717355783 x = -0.717355783 Simplifying x = -0.717355783

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.717355783, -0.717355783}

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