4x^2-9x-12=0

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Solution for 4x^2-9x-12=0 equation:


Simplifying
4x2 + -9x + -12 = 0

Reorder the terms:
-12 + -9x + 4x2 = 0

Solving
-12 + -9x + 4x2 = 0

Solving for variable 'x'.

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

Divide each side by '4'.
-3 + -2.25x + x2 = 0

Move the constant term to the right:

Add '3' to each side of the equation.
-3 + -2.25x + 3 + x2 = 0 + 3

Reorder the terms:
-3 + 3 + -2.25x + x2 = 0 + 3

Combine like terms: -3 + 3 = 0
0 + -2.25x + x2 = 0 + 3
-2.25x + x2 = 0 + 3

Combine like terms: 0 + 3 = 3
-2.25x + x2 = 3

The x term is -2.25x.  Take half its coefficient (-1.125).
Square it (1.265625) and add it to both sides.

Add '1.265625' to each side of the equation.
-2.25x + 1.265625 + x2 = 3 + 1.265625

Reorder the terms:
1.265625 + -2.25x + x2 = 3 + 1.265625

Combine like terms: 3 + 1.265625 = 4.265625
1.265625 + -2.25x + x2 = 4.265625

Factor a perfect square on the left side:
(x + -1.125)(x + -1.125) = 4.265625

Calculate the square root of the right side: 2.065338955

Break this problem into two subproblems by setting 
(x + -1.125) equal to 2.065338955 and -2.065338955.

Subproblem 1

x + -1.125 = 2.065338955 Simplifying x + -1.125 = 2.065338955 Reorder the terms: -1.125 + x = 2.065338955 Solving -1.125 + x = 2.065338955 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.125' to each side of the equation. -1.125 + 1.125 + x = 2.065338955 + 1.125 Combine like terms: -1.125 + 1.125 = 0.000 0.000 + x = 2.065338955 + 1.125 x = 2.065338955 + 1.125 Combine like terms: 2.065338955 + 1.125 = 3.190338955 x = 3.190338955 Simplifying x = 3.190338955

Subproblem 2

x + -1.125 = -2.065338955 Simplifying x + -1.125 = -2.065338955 Reorder the terms: -1.125 + x = -2.065338955 Solving -1.125 + x = -2.065338955 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '1.125' to each side of the equation. -1.125 + 1.125 + x = -2.065338955 + 1.125 Combine like terms: -1.125 + 1.125 = 0.000 0.000 + x = -2.065338955 + 1.125 x = -2.065338955 + 1.125 Combine like terms: -2.065338955 + 1.125 = -0.940338955 x = -0.940338955 Simplifying x = -0.940338955

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.190338955, -0.940338955}

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