x^2-6x-21.9=0

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Solution for x^2-6x-21.9=0 equation:


Simplifying
x2 + -6x + -21.9 = 0

Reorder the terms:
-21.9 + -6x + x2 = 0

Solving
-21.9 + -6x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '21.9' to each side of the equation.
-21.9 + -6x + 21.9 + x2 = 0 + 21.9

Reorder the terms:
-21.9 + 21.9 + -6x + x2 = 0 + 21.9

Combine like terms: -21.9 + 21.9 = 0.0
0.0 + -6x + x2 = 0 + 21.9
-6x + x2 = 0 + 21.9

Combine like terms: 0 + 21.9 = 21.9
-6x + x2 = 21.9

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 = 21.9 + 9

Reorder the terms:
9 + -6x + x2 = 21.9 + 9

Combine like terms: 21.9 + 9 = 30.9
9 + -6x + x2 = 30.9

Factor a perfect square on the left side:
(x + -3)(x + -3) = 30.9

Calculate the square root of the right side: 5.558776844

Break this problem into two subproblems by setting 
(x + -3) equal to 5.558776844 and -5.558776844.

Subproblem 1

x + -3 = 5.558776844 Simplifying x + -3 = 5.558776844 Reorder the terms: -3 + x = 5.558776844 Solving -3 + x = 5.558776844 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 = 5.558776844 + 3 Combine like terms: -3 + 3 = 0 0 + x = 5.558776844 + 3 x = 5.558776844 + 3 Combine like terms: 5.558776844 + 3 = 8.558776844 x = 8.558776844 Simplifying x = 8.558776844

Subproblem 2

x + -3 = -5.558776844 Simplifying x + -3 = -5.558776844 Reorder the terms: -3 + x = -5.558776844 Solving -3 + x = -5.558776844 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 = -5.558776844 + 3 Combine like terms: -3 + 3 = 0 0 + x = -5.558776844 + 3 x = -5.558776844 + 3 Combine like terms: -5.558776844 + 3 = -2.558776844 x = -2.558776844 Simplifying x = -2.558776844

Solution

The solution to the problem is based on the solutions from the subproblems. x = {8.558776844, -2.558776844}

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