3x^2-5x-18=0

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Solution for 3x^2-5x-18=0 equation:


Simplifying
3x2 + -5x + -18 = 0

Reorder the terms:
-18 + -5x + 3x2 = 0

Solving
-18 + -5x + 3x2 = 0

Solving for variable 'x'.

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

Divide each side by '3'.
-6 + -1.666666667x + x2 = 0

Move the constant term to the right:

Add '6' to each side of the equation.
-6 + -1.666666667x + 6 + x2 = 0 + 6

Reorder the terms:
-6 + 6 + -1.666666667x + x2 = 0 + 6

Combine like terms: -6 + 6 = 0
0 + -1.666666667x + x2 = 0 + 6
-1.666666667x + x2 = 0 + 6

Combine like terms: 0 + 6 = 6
-1.666666667x + x2 = 6

The x term is -1.666666667x.  Take half its coefficient (-0.8333333335).
Square it (0.6944444447) and add it to both sides.

Add '0.6944444447' to each side of the equation.
-1.666666667x + 0.6944444447 + x2 = 6 + 0.6944444447

Reorder the terms:
0.6944444447 + -1.666666667x + x2 = 6 + 0.6944444447

Combine like terms: 6 + 0.6944444447 = 6.6944444447
0.6944444447 + -1.666666667x + x2 = 6.6944444447

Factor a perfect square on the left side:
(x + -0.8333333335)(x + -0.8333333335) = 6.6944444447

Calculate the square root of the right side: 2.587362449

Break this problem into two subproblems by setting 
(x + -0.8333333335) equal to 2.587362449 and -2.587362449.

Subproblem 1

x + -0.8333333335 = 2.587362449 Simplifying x + -0.8333333335 = 2.587362449 Reorder the terms: -0.8333333335 + x = 2.587362449 Solving -0.8333333335 + x = 2.587362449 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.8333333335' to each side of the equation. -0.8333333335 + 0.8333333335 + x = 2.587362449 + 0.8333333335 Combine like terms: -0.8333333335 + 0.8333333335 = 0.0000000000 0.0000000000 + x = 2.587362449 + 0.8333333335 x = 2.587362449 + 0.8333333335 Combine like terms: 2.587362449 + 0.8333333335 = 3.4206957825 x = 3.4206957825 Simplifying x = 3.4206957825

Subproblem 2

x + -0.8333333335 = -2.587362449 Simplifying x + -0.8333333335 = -2.587362449 Reorder the terms: -0.8333333335 + x = -2.587362449 Solving -0.8333333335 + x = -2.587362449 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.8333333335' to each side of the equation. -0.8333333335 + 0.8333333335 + x = -2.587362449 + 0.8333333335 Combine like terms: -0.8333333335 + 0.8333333335 = 0.0000000000 0.0000000000 + x = -2.587362449 + 0.8333333335 x = -2.587362449 + 0.8333333335 Combine like terms: -2.587362449 + 0.8333333335 = -1.7540291155 x = -1.7540291155 Simplifying x = -1.7540291155

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.4206957825, -1.7540291155}

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