x^2-15=6x

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


Simplifying
x2 + -15 = 6x

Reorder the terms:
-15 + x2 = 6x

Solving
-15 + x2 = 6x

Solving for variable 'x'.

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

Combine like terms: 6x + -6x = 0
-15 + -6x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '15' to each side of the equation.
-15 + -6x + 15 + x2 = 0 + 15

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

Combine like terms: -15 + 15 = 0
0 + -6x + x2 = 0 + 15
-6x + x2 = 0 + 15

Combine like terms: 0 + 15 = 15
-6x + x2 = 15

The x term is -6x.  Take half its coefficient (-3).
Square it (9) and add it to both sides.

Add '9' to each side of the equation.
-6x + 9 + x2 = 15 + 9

Reorder the terms:
9 + -6x + x2 = 15 + 9

Combine like terms: 15 + 9 = 24
9 + -6x + x2 = 24

Factor a perfect square on the left side:
(x + -3)(x + -3) = 24

Calculate the square root of the right side: 4.898979486

Break this problem into two subproblems by setting 
(x + -3) equal to 4.898979486 and -4.898979486.

Subproblem 1

x + -3 = 4.898979486 Simplifying x + -3 = 4.898979486 Reorder the terms: -3 + x = 4.898979486 Solving -3 + x = 4.898979486 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3' to each side of the equation. -3 + 3 + x = 4.898979486 + 3 Combine like terms: -3 + 3 = 0 0 + x = 4.898979486 + 3 x = 4.898979486 + 3 Combine like terms: 4.898979486 + 3 = 7.898979486 x = 7.898979486 Simplifying x = 7.898979486

Subproblem 2

x + -3 = -4.898979486 Simplifying x + -3 = -4.898979486 Reorder the terms: -3 + x = -4.898979486 Solving -3 + x = -4.898979486 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '3' to each side of the equation. -3 + 3 + x = -4.898979486 + 3 Combine like terms: -3 + 3 = 0 0 + x = -4.898979486 + 3 x = -4.898979486 + 3 Combine like terms: -4.898979486 + 3 = -1.898979486 x = -1.898979486 Simplifying x = -1.898979486

Solution

The solution to the problem is based on the solutions from the subproblems. x = {7.898979486, -1.898979486}

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