x^2-18x=-9

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Solution for x^2-18x=-9 equation:


Simplifying
x2 + -18x = -9

Reorder the terms:
-18x + x2 = -9

Solving
-18x + x2 = -9

Solving for variable 'x'.

Reorder the terms:
9 + -18x + x2 = -9 + 9

Combine like terms: -9 + 9 = 0
9 + -18x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-9' to each side of the equation.
9 + -18x + -9 + x2 = 0 + -9

Reorder the terms:
9 + -9 + -18x + x2 = 0 + -9

Combine like terms: 9 + -9 = 0
0 + -18x + x2 = 0 + -9
-18x + x2 = 0 + -9

Combine like terms: 0 + -9 = -9
-18x + x2 = -9

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 = -9 + 81

Reorder the terms:
81 + -18x + x2 = -9 + 81

Combine like terms: -9 + 81 = 72
81 + -18x + x2 = 72

Factor a perfect square on the left side:
(x + -9)(x + -9) = 72

Calculate the square root of the right side: 8.485281374

Break this problem into two subproblems by setting 
(x + -9) equal to 8.485281374 and -8.485281374.

Subproblem 1

x + -9 = 8.485281374 Simplifying x + -9 = 8.485281374 Reorder the terms: -9 + x = 8.485281374 Solving -9 + x = 8.485281374 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 = 8.485281374 + 9 Combine like terms: -9 + 9 = 0 0 + x = 8.485281374 + 9 x = 8.485281374 + 9 Combine like terms: 8.485281374 + 9 = 17.485281374 x = 17.485281374 Simplifying x = 17.485281374

Subproblem 2

x + -9 = -8.485281374 Simplifying x + -9 = -8.485281374 Reorder the terms: -9 + x = -8.485281374 Solving -9 + x = -8.485281374 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 = -8.485281374 + 9 Combine like terms: -9 + 9 = 0 0 + x = -8.485281374 + 9 x = -8.485281374 + 9 Combine like terms: -8.485281374 + 9 = 0.514718626 x = 0.514718626 Simplifying x = 0.514718626

Solution

The solution to the problem is based on the solutions from the subproblems. x = {17.485281374, 0.514718626}

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