15x^2+18x-7=0

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


Simplifying
15x2 + 18x + -7 = 0

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

Solving
-7 + 18x + 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'.
-0.4666666667 + 1.2x + x2 = 0

Move the constant term to the right:

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

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

Combine like terms: -0.4666666667 + 0.4666666667 = 0.0000000000
0.0000000000 + 1.2x + x2 = 0 + 0.4666666667
1.2x + x2 = 0 + 0.4666666667

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

The x term is 1.2x.  Take half its coefficient (0.6).
Square it (0.36) and add it to both sides.

Add '0.36' to each side of the equation.
1.2x + 0.36 + x2 = 0.4666666667 + 0.36

Reorder the terms:
0.36 + 1.2x + x2 = 0.4666666667 + 0.36

Combine like terms: 0.4666666667 + 0.36 = 0.8266666667
0.36 + 1.2x + x2 = 0.8266666667

Factor a perfect square on the left side:
(x + 0.6)(x + 0.6) = 0.8266666667

Calculate the square root of the right side: 0.909212113

Break this problem into two subproblems by setting 
(x + 0.6) equal to 0.909212113 and -0.909212113.

Subproblem 1

x + 0.6 = 0.909212113 Simplifying x + 0.6 = 0.909212113 Reorder the terms: 0.6 + x = 0.909212113 Solving 0.6 + x = 0.909212113 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.6' to each side of the equation. 0.6 + -0.6 + x = 0.909212113 + -0.6 Combine like terms: 0.6 + -0.6 = 0.0 0.0 + x = 0.909212113 + -0.6 x = 0.909212113 + -0.6 Combine like terms: 0.909212113 + -0.6 = 0.309212113 x = 0.309212113 Simplifying x = 0.309212113

Subproblem 2

x + 0.6 = -0.909212113 Simplifying x + 0.6 = -0.909212113 Reorder the terms: 0.6 + x = -0.909212113 Solving 0.6 + x = -0.909212113 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.6' to each side of the equation. 0.6 + -0.6 + x = -0.909212113 + -0.6 Combine like terms: 0.6 + -0.6 = 0.0 0.0 + x = -0.909212113 + -0.6 x = -0.909212113 + -0.6 Combine like terms: -0.909212113 + -0.6 = -1.509212113 x = -1.509212113 Simplifying x = -1.509212113

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.309212113, -1.509212113}

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