15x^2-6x-8=0

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Solution for 15x^2-6x-8=0 equation:


Simplifying
15x2 + -6x + -8 = 0

Reorder the terms:
-8 + -6x + 15x2 = 0

Solving
-8 + -6x + 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'.
-0.5333333333 + -0.4x + x2 = 0

Move the constant term to the right:

Add '0.5333333333' to each side of the equation.
-0.5333333333 + -0.4x + 0.5333333333 + x2 = 0 + 0.5333333333

Reorder the terms:
-0.5333333333 + 0.5333333333 + -0.4x + x2 = 0 + 0.5333333333

Combine like terms: -0.5333333333 + 0.5333333333 = 0.0000000000
0.0000000000 + -0.4x + x2 = 0 + 0.5333333333
-0.4x + x2 = 0 + 0.5333333333

Combine like terms: 0 + 0.5333333333 = 0.5333333333
-0.4x + x2 = 0.5333333333

The x term is -0.4x.  Take half its coefficient (-0.2).
Square it (0.04) and add it to both sides.

Add '0.04' to each side of the equation.
-0.4x + 0.04 + x2 = 0.5333333333 + 0.04

Reorder the terms:
0.04 + -0.4x + x2 = 0.5333333333 + 0.04

Combine like terms: 0.5333333333 + 0.04 = 0.5733333333
0.04 + -0.4x + x2 = 0.5733333333

Factor a perfect square on the left side:
(x + -0.2)(x + -0.2) = 0.5733333333

Calculate the square root of the right side: 0.757187779

Break this problem into two subproblems by setting 
(x + -0.2) equal to 0.757187779 and -0.757187779.

Subproblem 1

x + -0.2 = 0.757187779 Simplifying x + -0.2 = 0.757187779 Reorder the terms: -0.2 + x = 0.757187779 Solving -0.2 + x = 0.757187779 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.2' to each side of the equation. -0.2 + 0.2 + x = 0.757187779 + 0.2 Combine like terms: -0.2 + 0.2 = 0.0 0.0 + x = 0.757187779 + 0.2 x = 0.757187779 + 0.2 Combine like terms: 0.757187779 + 0.2 = 0.957187779 x = 0.957187779 Simplifying x = 0.957187779

Subproblem 2

x + -0.2 = -0.757187779 Simplifying x + -0.2 = -0.757187779 Reorder the terms: -0.2 + x = -0.757187779 Solving -0.2 + x = -0.757187779 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.2' to each side of the equation. -0.2 + 0.2 + x = -0.757187779 + 0.2 Combine like terms: -0.2 + 0.2 = 0.0 0.0 + x = -0.757187779 + 0.2 x = -0.757187779 + 0.2 Combine like terms: -0.757187779 + 0.2 = -0.557187779 x = -0.557187779 Simplifying x = -0.557187779

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.957187779, -0.557187779}

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