3x^2+20x-15=0

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Solution for 3x^2+20x-15=0 equation:


Simplifying
3x2 + 20x + -15 = 0

Reorder the terms:
-15 + 20x + 3x2 = 0

Solving
-15 + 20x + 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'.
-5 + 6.666666667x + x2 = 0

Move the constant term to the right:

Add '5' to each side of the equation.
-5 + 6.666666667x + 5 + x2 = 0 + 5

Reorder the terms:
-5 + 5 + 6.666666667x + x2 = 0 + 5

Combine like terms: -5 + 5 = 0
0 + 6.666666667x + x2 = 0 + 5
6.666666667x + x2 = 0 + 5

Combine like terms: 0 + 5 = 5
6.666666667x + x2 = 5

The x term is 6.666666667x.  Take half its coefficient (3.333333334).
Square it (11.11111112) and add it to both sides.

Add '11.11111112' to each side of the equation.
6.666666667x + 11.11111112 + x2 = 5 + 11.11111112

Reorder the terms:
11.11111112 + 6.666666667x + x2 = 5 + 11.11111112

Combine like terms: 5 + 11.11111112 = 16.11111112
11.11111112 + 6.666666667x + x2 = 16.11111112

Factor a perfect square on the left side:
(x + 3.333333334)(x + 3.333333334) = 16.11111112

Calculate the square root of the right side: 4.013864861

Break this problem into two subproblems by setting 
(x + 3.333333334) equal to 4.013864861 and -4.013864861.

Subproblem 1

x + 3.333333334 = 4.013864861 Simplifying x + 3.333333334 = 4.013864861 Reorder the terms: 3.333333334 + x = 4.013864861 Solving 3.333333334 + x = 4.013864861 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.333333334' to each side of the equation. 3.333333334 + -3.333333334 + x = 4.013864861 + -3.333333334 Combine like terms: 3.333333334 + -3.333333334 = 0.000000000 0.000000000 + x = 4.013864861 + -3.333333334 x = 4.013864861 + -3.333333334 Combine like terms: 4.013864861 + -3.333333334 = 0.680531527 x = 0.680531527 Simplifying x = 0.680531527

Subproblem 2

x + 3.333333334 = -4.013864861 Simplifying x + 3.333333334 = -4.013864861 Reorder the terms: 3.333333334 + x = -4.013864861 Solving 3.333333334 + x = -4.013864861 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.333333334' to each side of the equation. 3.333333334 + -3.333333334 + x = -4.013864861 + -3.333333334 Combine like terms: 3.333333334 + -3.333333334 = 0.000000000 0.000000000 + x = -4.013864861 + -3.333333334 x = -4.013864861 + -3.333333334 Combine like terms: -4.013864861 + -3.333333334 = -7.347198195 x = -7.347198195 Simplifying x = -7.347198195

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.680531527, -7.347198195}

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