-18x+42=x^2-24x-81

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Solution for -18x+42=x^2-24x-81 equation:


Simplifying
-18x + 42 = x2 + -24x + -81

Reorder the terms:
42 + -18x = x2 + -24x + -81

Reorder the terms:
42 + -18x = -81 + -24x + x2

Solving
42 + -18x = -81 + -24x + x2

Solving for variable 'x'.

Reorder the terms:
42 + 81 + -18x + 24x + -1x2 = -81 + -24x + x2 + 81 + 24x + -1x2

Combine like terms: 42 + 81 = 123
123 + -18x + 24x + -1x2 = -81 + -24x + x2 + 81 + 24x + -1x2

Combine like terms: -18x + 24x = 6x
123 + 6x + -1x2 = -81 + -24x + x2 + 81 + 24x + -1x2

Reorder the terms:
123 + 6x + -1x2 = -81 + 81 + -24x + 24x + x2 + -1x2

Combine like terms: -81 + 81 = 0
123 + 6x + -1x2 = 0 + -24x + 24x + x2 + -1x2
123 + 6x + -1x2 = -24x + 24x + x2 + -1x2

Combine like terms: -24x + 24x = 0
123 + 6x + -1x2 = 0 + x2 + -1x2
123 + 6x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
123 + 6x + -1x2 = 0

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

Divide each side by '-1'.
-123 + -6x + x2 = 0

Move the constant term to the right:

Add '123' to each side of the equation.
-123 + -6x + 123 + x2 = 0 + 123

Reorder the terms:
-123 + 123 + -6x + x2 = 0 + 123

Combine like terms: -123 + 123 = 0
0 + -6x + x2 = 0 + 123
-6x + x2 = 0 + 123

Combine like terms: 0 + 123 = 123
-6x + x2 = 123

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 = 123 + 9

Reorder the terms:
9 + -6x + x2 = 123 + 9

Combine like terms: 123 + 9 = 132
9 + -6x + x2 = 132

Factor a perfect square on the left side:
(x + -3)(x + -3) = 132

Calculate the square root of the right side: 11.489125293

Break this problem into two subproblems by setting 
(x + -3) equal to 11.489125293 and -11.489125293.

Subproblem 1

x + -3 = 11.489125293 Simplifying x + -3 = 11.489125293 Reorder the terms: -3 + x = 11.489125293 Solving -3 + x = 11.489125293 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 = 11.489125293 + 3 Combine like terms: -3 + 3 = 0 0 + x = 11.489125293 + 3 x = 11.489125293 + 3 Combine like terms: 11.489125293 + 3 = 14.489125293 x = 14.489125293 Simplifying x = 14.489125293

Subproblem 2

x + -3 = -11.489125293 Simplifying x + -3 = -11.489125293 Reorder the terms: -3 + x = -11.489125293 Solving -3 + x = -11.489125293 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 = -11.489125293 + 3 Combine like terms: -3 + 3 = 0 0 + x = -11.489125293 + 3 x = -11.489125293 + 3 Combine like terms: -11.489125293 + 3 = -8.489125293 x = -8.489125293 Simplifying x = -8.489125293

Solution

The solution to the problem is based on the solutions from the subproblems. x = {14.489125293, -8.489125293}

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