x^2-15x+42=0

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Solution for x^2-15x+42=0 equation:


Simplifying
x2 + -15x + 42 = 0

Reorder the terms:
42 + -15x + x2 = 0

Solving
42 + -15x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-42' to each side of the equation.
42 + -15x + -42 + x2 = 0 + -42

Reorder the terms:
42 + -42 + -15x + x2 = 0 + -42

Combine like terms: 42 + -42 = 0
0 + -15x + x2 = 0 + -42
-15x + x2 = 0 + -42

Combine like terms: 0 + -42 = -42
-15x + x2 = -42

The x term is -15x.  Take half its coefficient (-7.5).
Square it (56.25) and add it to both sides.

Add '56.25' to each side of the equation.
-15x + 56.25 + x2 = -42 + 56.25

Reorder the terms:
56.25 + -15x + x2 = -42 + 56.25

Combine like terms: -42 + 56.25 = 14.25
56.25 + -15x + x2 = 14.25

Factor a perfect square on the left side:
(x + -7.5)(x + -7.5) = 14.25

Calculate the square root of the right side: 3.774917218

Break this problem into two subproblems by setting 
(x + -7.5) equal to 3.774917218 and -3.774917218.

Subproblem 1

x + -7.5 = 3.774917218 Simplifying x + -7.5 = 3.774917218 Reorder the terms: -7.5 + x = 3.774917218 Solving -7.5 + x = 3.774917218 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '7.5' to each side of the equation. -7.5 + 7.5 + x = 3.774917218 + 7.5 Combine like terms: -7.5 + 7.5 = 0.0 0.0 + x = 3.774917218 + 7.5 x = 3.774917218 + 7.5 Combine like terms: 3.774917218 + 7.5 = 11.274917218 x = 11.274917218 Simplifying x = 11.274917218

Subproblem 2

x + -7.5 = -3.774917218 Simplifying x + -7.5 = -3.774917218 Reorder the terms: -7.5 + x = -3.774917218 Solving -7.5 + x = -3.774917218 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '7.5' to each side of the equation. -7.5 + 7.5 + x = -3.774917218 + 7.5 Combine like terms: -7.5 + 7.5 = 0.0 0.0 + x = -3.774917218 + 7.5 x = -3.774917218 + 7.5 Combine like terms: -3.774917218 + 7.5 = 3.725082782 x = 3.725082782 Simplifying x = 3.725082782

Solution

The solution to the problem is based on the solutions from the subproblems. x = {11.274917218, 3.725082782}

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