5x^2-9x-12=0

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Solution for 5x^2-9x-12=0 equation:


Simplifying
5x2 + -9x + -12 = 0

Reorder the terms:
-12 + -9x + 5x2 = 0

Solving
-12 + -9x + 5x2 = 0

Solving for variable 'x'.

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

Divide each side by '5'.
-2.4 + -1.8x + x2 = 0

Move the constant term to the right:

Add '2.4' to each side of the equation.
-2.4 + -1.8x + 2.4 + x2 = 0 + 2.4

Reorder the terms:
-2.4 + 2.4 + -1.8x + x2 = 0 + 2.4

Combine like terms: -2.4 + 2.4 = 0.0
0.0 + -1.8x + x2 = 0 + 2.4
-1.8x + x2 = 0 + 2.4

Combine like terms: 0 + 2.4 = 2.4
-1.8x + x2 = 2.4

The x term is -1.8x.  Take half its coefficient (-0.9).
Square it (0.81) and add it to both sides.

Add '0.81' to each side of the equation.
-1.8x + 0.81 + x2 = 2.4 + 0.81

Reorder the terms:
0.81 + -1.8x + x2 = 2.4 + 0.81

Combine like terms: 2.4 + 0.81 = 3.21
0.81 + -1.8x + x2 = 3.21

Factor a perfect square on the left side:
(x + -0.9)(x + -0.9) = 3.21

Calculate the square root of the right side: 1.791647287

Break this problem into two subproblems by setting 
(x + -0.9) equal to 1.791647287 and -1.791647287.

Subproblem 1

x + -0.9 = 1.791647287 Simplifying x + -0.9 = 1.791647287 Reorder the terms: -0.9 + x = 1.791647287 Solving -0.9 + x = 1.791647287 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.9' to each side of the equation. -0.9 + 0.9 + x = 1.791647287 + 0.9 Combine like terms: -0.9 + 0.9 = 0.0 0.0 + x = 1.791647287 + 0.9 x = 1.791647287 + 0.9 Combine like terms: 1.791647287 + 0.9 = 2.691647287 x = 2.691647287 Simplifying x = 2.691647287

Subproblem 2

x + -0.9 = -1.791647287 Simplifying x + -0.9 = -1.791647287 Reorder the terms: -0.9 + x = -1.791647287 Solving -0.9 + x = -1.791647287 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.9' to each side of the equation. -0.9 + 0.9 + x = -1.791647287 + 0.9 Combine like terms: -0.9 + 0.9 = 0.0 0.0 + x = -1.791647287 + 0.9 x = -1.791647287 + 0.9 Combine like terms: -1.791647287 + 0.9 = -0.891647287 x = -0.891647287 Simplifying x = -0.891647287

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.691647287, -0.891647287}

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