15x^2-7x-18=0

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Solution for 15x^2-7x-18=0 equation:


Simplifying
15x2 + -7x + -18 = 0

Reorder the terms:
-18 + -7x + 15x2 = 0

Solving
-18 + -7x + 15x2 = 0

Solving for variable 'x'.

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

Divide each side by '15'.
-1.2 + -0.4666666667x + x2 = 0

Move the constant term to the right:

Add '1.2' to each side of the equation.
-1.2 + -0.4666666667x + 1.2 + x2 = 0 + 1.2

Reorder the terms:
-1.2 + 1.2 + -0.4666666667x + x2 = 0 + 1.2

Combine like terms: -1.2 + 1.2 = 0.0
0.0 + -0.4666666667x + x2 = 0 + 1.2
-0.4666666667x + x2 = 0 + 1.2

Combine like terms: 0 + 1.2 = 1.2
-0.4666666667x + x2 = 1.2

The x term is -0.4666666667x.  Take half its coefficient (-0.2333333334).
Square it (0.05444444448) and add it to both sides.

Add '0.05444444448' to each side of the equation.
-0.4666666667x + 0.05444444448 + x2 = 1.2 + 0.05444444448

Reorder the terms:
0.05444444448 + -0.4666666667x + x2 = 1.2 + 0.05444444448

Combine like terms: 1.2 + 0.05444444448 = 1.25444444448
0.05444444448 + -0.4666666667x + x2 = 1.25444444448

Factor a perfect square on the left side:
(x + -0.2333333334)(x + -0.2333333334) = 1.25444444448

Calculate the square root of the right side: 1.120019841

Break this problem into two subproblems by setting 
(x + -0.2333333334) equal to 1.120019841 and -1.120019841.

Subproblem 1

x + -0.2333333334 = 1.120019841 Simplifying x + -0.2333333334 = 1.120019841 Reorder the terms: -0.2333333334 + x = 1.120019841 Solving -0.2333333334 + x = 1.120019841 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.2333333334' to each side of the equation. -0.2333333334 + 0.2333333334 + x = 1.120019841 + 0.2333333334 Combine like terms: -0.2333333334 + 0.2333333334 = 0.0000000000 0.0000000000 + x = 1.120019841 + 0.2333333334 x = 1.120019841 + 0.2333333334 Combine like terms: 1.120019841 + 0.2333333334 = 1.3533531744 x = 1.3533531744 Simplifying x = 1.3533531744

Subproblem 2

x + -0.2333333334 = -1.120019841 Simplifying x + -0.2333333334 = -1.120019841 Reorder the terms: -0.2333333334 + x = -1.120019841 Solving -0.2333333334 + x = -1.120019841 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.2333333334' to each side of the equation. -0.2333333334 + 0.2333333334 + x = -1.120019841 + 0.2333333334 Combine like terms: -0.2333333334 + 0.2333333334 = 0.0000000000 0.0000000000 + x = -1.120019841 + 0.2333333334 x = -1.120019841 + 0.2333333334 Combine like terms: -1.120019841 + 0.2333333334 = -0.8866865076 x = -0.8866865076 Simplifying x = -0.8866865076

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.3533531744, -0.8866865076}

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