8x^2+12x=9

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Solution for 8x^2+12x=9 equation:


Simplifying
8x2 + 12x = 9

Reorder the terms:
12x + 8x2 = 9

Solving
12x + 8x2 = 9

Solving for variable 'x'.

Reorder the terms:
-9 + 12x + 8x2 = 9 + -9

Combine like terms: 9 + -9 = 0
-9 + 12x + 8x2 = 0

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

Divide each side by '8'.
-1.125 + 1.5x + x2 = 0

Move the constant term to the right:

Add '1.125' to each side of the equation.
-1.125 + 1.5x + 1.125 + x2 = 0 + 1.125

Reorder the terms:
-1.125 + 1.125 + 1.5x + x2 = 0 + 1.125

Combine like terms: -1.125 + 1.125 = 0.000
0.000 + 1.5x + x2 = 0 + 1.125
1.5x + x2 = 0 + 1.125

Combine like terms: 0 + 1.125 = 1.125
1.5x + x2 = 1.125

The x term is 1.5x.  Take half its coefficient (0.75).
Square it (0.5625) and add it to both sides.

Add '0.5625' to each side of the equation.
1.5x + 0.5625 + x2 = 1.125 + 0.5625

Reorder the terms:
0.5625 + 1.5x + x2 = 1.125 + 0.5625

Combine like terms: 1.125 + 0.5625 = 1.6875
0.5625 + 1.5x + x2 = 1.6875

Factor a perfect square on the left side:
(x + 0.75)(x + 0.75) = 1.6875

Calculate the square root of the right side: 1.299038106

Break this problem into two subproblems by setting 
(x + 0.75) equal to 1.299038106 and -1.299038106.

Subproblem 1

x + 0.75 = 1.299038106 Simplifying x + 0.75 = 1.299038106 Reorder the terms: 0.75 + x = 1.299038106 Solving 0.75 + x = 1.299038106 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.75' to each side of the equation. 0.75 + -0.75 + x = 1.299038106 + -0.75 Combine like terms: 0.75 + -0.75 = 0.00 0.00 + x = 1.299038106 + -0.75 x = 1.299038106 + -0.75 Combine like terms: 1.299038106 + -0.75 = 0.549038106 x = 0.549038106 Simplifying x = 0.549038106

Subproblem 2

x + 0.75 = -1.299038106 Simplifying x + 0.75 = -1.299038106 Reorder the terms: 0.75 + x = -1.299038106 Solving 0.75 + x = -1.299038106 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.75' to each side of the equation. 0.75 + -0.75 + x = -1.299038106 + -0.75 Combine like terms: 0.75 + -0.75 = 0.00 0.00 + x = -1.299038106 + -0.75 x = -1.299038106 + -0.75 Combine like terms: -1.299038106 + -0.75 = -2.049038106 x = -2.049038106 Simplifying x = -2.049038106

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.549038106, -2.049038106}

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