x^2+6x=84

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Solution for x^2+6x=84 equation:


Simplifying
x2 + 6x = 84

Reorder the terms:
6x + x2 = 84

Solving
6x + x2 = 84

Solving for variable 'x'.

Reorder the terms:
-84 + 6x + x2 = 84 + -84

Combine like terms: 84 + -84 = 0
-84 + 6x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '84' to each side of the equation.
-84 + 6x + 84 + x2 = 0 + 84

Reorder the terms:
-84 + 84 + 6x + x2 = 0 + 84

Combine like terms: -84 + 84 = 0
0 + 6x + x2 = 0 + 84
6x + x2 = 0 + 84

Combine like terms: 0 + 84 = 84
6x + x2 = 84

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 = 84 + 9

Reorder the terms:
9 + 6x + x2 = 84 + 9

Combine like terms: 84 + 9 = 93
9 + 6x + x2 = 93

Factor a perfect square on the left side:
(x + 3)(x + 3) = 93

Calculate the square root of the right side: 9.643650761

Break this problem into two subproblems by setting 
(x + 3) equal to 9.643650761 and -9.643650761.

Subproblem 1

x + 3 = 9.643650761 Simplifying x + 3 = 9.643650761 Reorder the terms: 3 + x = 9.643650761 Solving 3 + x = 9.643650761 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 = 9.643650761 + -3 Combine like terms: 3 + -3 = 0 0 + x = 9.643650761 + -3 x = 9.643650761 + -3 Combine like terms: 9.643650761 + -3 = 6.643650761 x = 6.643650761 Simplifying x = 6.643650761

Subproblem 2

x + 3 = -9.643650761 Simplifying x + 3 = -9.643650761 Reorder the terms: 3 + x = -9.643650761 Solving 3 + x = -9.643650761 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 = -9.643650761 + -3 Combine like terms: 3 + -3 = 0 0 + x = -9.643650761 + -3 x = -9.643650761 + -3 Combine like terms: -9.643650761 + -3 = -12.643650761 x = -12.643650761 Simplifying x = -12.643650761

Solution

The solution to the problem is based on the solutions from the subproblems. x = {6.643650761, -12.643650761}

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