x^2+18x-54=0

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Solution for x^2+18x-54=0 equation:


Simplifying
x2 + 18x + -54 = 0

Reorder the terms:
-54 + 18x + x2 = 0

Solving
-54 + 18x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '54' to each side of the equation.
-54 + 18x + 54 + x2 = 0 + 54

Reorder the terms:
-54 + 54 + 18x + x2 = 0 + 54

Combine like terms: -54 + 54 = 0
0 + 18x + x2 = 0 + 54
18x + x2 = 0 + 54

Combine like terms: 0 + 54 = 54
18x + x2 = 54

The x term is 18x.  Take half its coefficient (9).
Square it (81) and add it to both sides.

Add '81' to each side of the equation.
18x + 81 + x2 = 54 + 81

Reorder the terms:
81 + 18x + x2 = 54 + 81

Combine like terms: 54 + 81 = 135
81 + 18x + x2 = 135

Factor a perfect square on the left side:
(x + 9)(x + 9) = 135

Calculate the square root of the right side: 11.618950039

Break this problem into two subproblems by setting 
(x + 9) equal to 11.618950039 and -11.618950039.

Subproblem 1

x + 9 = 11.618950039 Simplifying x + 9 = 11.618950039 Reorder the terms: 9 + x = 11.618950039 Solving 9 + x = 11.618950039 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + x = 11.618950039 + -9 Combine like terms: 9 + -9 = 0 0 + x = 11.618950039 + -9 x = 11.618950039 + -9 Combine like terms: 11.618950039 + -9 = 2.618950039 x = 2.618950039 Simplifying x = 2.618950039

Subproblem 2

x + 9 = -11.618950039 Simplifying x + 9 = -11.618950039 Reorder the terms: 9 + x = -11.618950039 Solving 9 + x = -11.618950039 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-9' to each side of the equation. 9 + -9 + x = -11.618950039 + -9 Combine like terms: 9 + -9 = 0 0 + x = -11.618950039 + -9 x = -11.618950039 + -9 Combine like terms: -11.618950039 + -9 = -20.618950039 x = -20.618950039 Simplifying x = -20.618950039

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.618950039, -20.618950039}

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