15x^2+4x-9=0

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Solution for 15x^2+4x-9=0 equation:


Simplifying
15x2 + 4x + -9 = 0

Reorder the terms:
-9 + 4x + 15x2 = 0

Solving
-9 + 4x + 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'.
-0.6 + 0.2666666667x + x2 = 0

Move the constant term to the right:

Add '0.6' to each side of the equation.
-0.6 + 0.2666666667x + 0.6 + x2 = 0 + 0.6

Reorder the terms:
-0.6 + 0.6 + 0.2666666667x + x2 = 0 + 0.6

Combine like terms: -0.6 + 0.6 = 0.0
0.0 + 0.2666666667x + x2 = 0 + 0.6
0.2666666667x + x2 = 0 + 0.6

Combine like terms: 0 + 0.6 = 0.6
0.2666666667x + x2 = 0.6

The x term is 0.2666666667x.  Take half its coefficient (0.1333333334).
Square it (0.01777777780) and add it to both sides.

Add '0.01777777780' to each side of the equation.
0.2666666667x + 0.01777777780 + x2 = 0.6 + 0.01777777780

Reorder the terms:
0.01777777780 + 0.2666666667x + x2 = 0.6 + 0.01777777780

Combine like terms: 0.6 + 0.01777777780 = 0.6177777778
0.01777777780 + 0.2666666667x + x2 = 0.6177777778

Factor a perfect square on the left side:
(x + 0.1333333334)(x + 0.1333333334) = 0.6177777778

Calculate the square root of the right side: 0.785988408

Break this problem into two subproblems by setting 
(x + 0.1333333334) equal to 0.785988408 and -0.785988408.

Subproblem 1

x + 0.1333333334 = 0.785988408 Simplifying x + 0.1333333334 = 0.785988408 Reorder the terms: 0.1333333334 + x = 0.785988408 Solving 0.1333333334 + x = 0.785988408 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.1333333334' to each side of the equation. 0.1333333334 + -0.1333333334 + x = 0.785988408 + -0.1333333334 Combine like terms: 0.1333333334 + -0.1333333334 = 0.0000000000 0.0000000000 + x = 0.785988408 + -0.1333333334 x = 0.785988408 + -0.1333333334 Combine like terms: 0.785988408 + -0.1333333334 = 0.6526550746 x = 0.6526550746 Simplifying x = 0.6526550746

Subproblem 2

x + 0.1333333334 = -0.785988408 Simplifying x + 0.1333333334 = -0.785988408 Reorder the terms: 0.1333333334 + x = -0.785988408 Solving 0.1333333334 + x = -0.785988408 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.1333333334' to each side of the equation. 0.1333333334 + -0.1333333334 + x = -0.785988408 + -0.1333333334 Combine like terms: 0.1333333334 + -0.1333333334 = 0.0000000000 0.0000000000 + x = -0.785988408 + -0.1333333334 x = -0.785988408 + -0.1333333334 Combine like terms: -0.785988408 + -0.1333333334 = -0.9193217414 x = -0.9193217414 Simplifying x = -0.9193217414

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.6526550746, -0.9193217414}

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