3x^2+18x=8

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Solution for 3x^2+18x=8 equation:


Simplifying
3x2 + 18x = 8

Reorder the terms:
18x + 3x2 = 8

Solving
18x + 3x2 = 8

Solving for variable 'x'.

Reorder the terms:
-8 + 18x + 3x2 = 8 + -8

Combine like terms: 8 + -8 = 0
-8 + 18x + 3x2 = 0

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

Divide each side by '3'.
-2.666666667 + 6x + x2 = 0

Move the constant term to the right:

Add '2.666666667' to each side of the equation.
-2.666666667 + 6x + 2.666666667 + x2 = 0 + 2.666666667

Reorder the terms:
-2.666666667 + 2.666666667 + 6x + x2 = 0 + 2.666666667

Combine like terms: -2.666666667 + 2.666666667 = 0.000000000
0.000000000 + 6x + x2 = 0 + 2.666666667
6x + x2 = 0 + 2.666666667

Combine like terms: 0 + 2.666666667 = 2.666666667
6x + x2 = 2.666666667

The x term is 6x.  Take half its coefficient (3).
Square it (9) and add it to both sides.

Add '9' to each side of the equation.
6x + 9 + x2 = 2.666666667 + 9

Reorder the terms:
9 + 6x + x2 = 2.666666667 + 9

Combine like terms: 2.666666667 + 9 = 11.666666667
9 + 6x + x2 = 11.666666667

Factor a perfect square on the left side:
(x + 3)(x + 3) = 11.666666667

Calculate the square root of the right side: 3.415650255

Break this problem into two subproblems by setting 
(x + 3) equal to 3.415650255 and -3.415650255.

Subproblem 1

x + 3 = 3.415650255 Simplifying x + 3 = 3.415650255 Reorder the terms: 3 + x = 3.415650255 Solving 3 + x = 3.415650255 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3' to each side of the equation. 3 + -3 + x = 3.415650255 + -3 Combine like terms: 3 + -3 = 0 0 + x = 3.415650255 + -3 x = 3.415650255 + -3 Combine like terms: 3.415650255 + -3 = 0.415650255 x = 0.415650255 Simplifying x = 0.415650255

Subproblem 2

x + 3 = -3.415650255 Simplifying x + 3 = -3.415650255 Reorder the terms: 3 + x = -3.415650255 Solving 3 + x = -3.415650255 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3' to each side of the equation. 3 + -3 + x = -3.415650255 + -3 Combine like terms: 3 + -3 = 0 0 + x = -3.415650255 + -3 x = -3.415650255 + -3 Combine like terms: -3.415650255 + -3 = -6.415650255 x = -6.415650255 Simplifying x = -6.415650255

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.415650255, -6.415650255}

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