-x^2+18x+100=0

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Solution for -x^2+18x+100=0 equation:


Simplifying
-1x2 + 18x + 100 = 0

Reorder the terms:
100 + 18x + -1x2 = 0

Solving
100 + 18x + -1x2 = 0

Solving for variable 'x'.

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-100 + -18x + x2 = 0

Move the constant term to the right:

Add '100' to each side of the equation.
-100 + -18x + 100 + x2 = 0 + 100

Reorder the terms:
-100 + 100 + -18x + x2 = 0 + 100

Combine like terms: -100 + 100 = 0
0 + -18x + x2 = 0 + 100
-18x + x2 = 0 + 100

Combine like terms: 0 + 100 = 100
-18x + x2 = 100

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 = 100 + 81

Reorder the terms:
81 + -18x + x2 = 100 + 81

Combine like terms: 100 + 81 = 181
81 + -18x + x2 = 181

Factor a perfect square on the left side:
(x + -9)(x + -9) = 181

Calculate the square root of the right side: 13.453624047

Break this problem into two subproblems by setting 
(x + -9) equal to 13.453624047 and -13.453624047.

Subproblem 1

x + -9 = 13.453624047 Simplifying x + -9 = 13.453624047 Reorder the terms: -9 + x = 13.453624047 Solving -9 + x = 13.453624047 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 = 13.453624047 + 9 Combine like terms: -9 + 9 = 0 0 + x = 13.453624047 + 9 x = 13.453624047 + 9 Combine like terms: 13.453624047 + 9 = 22.453624047 x = 22.453624047 Simplifying x = 22.453624047

Subproblem 2

x + -9 = -13.453624047 Simplifying x + -9 = -13.453624047 Reorder the terms: -9 + x = -13.453624047 Solving -9 + x = -13.453624047 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 = -13.453624047 + 9 Combine like terms: -9 + 9 = 0 0 + x = -13.453624047 + 9 x = -13.453624047 + 9 Combine like terms: -13.453624047 + 9 = -4.453624047 x = -4.453624047 Simplifying x = -4.453624047

Solution

The solution to the problem is based on the solutions from the subproblems. x = {22.453624047, -4.453624047}

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