x^2+16x=-9

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Solution for x^2+16x=-9 equation:


Simplifying
x2 + 16x = -9

Reorder the terms:
16x + x2 = -9

Solving
16x + x2 = -9

Solving for variable 'x'.

Reorder the terms:
9 + 16x + x2 = -9 + 9

Combine like terms: -9 + 9 = 0
9 + 16x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-9' to each side of the equation.
9 + 16x + -9 + x2 = 0 + -9

Reorder the terms:
9 + -9 + 16x + x2 = 0 + -9

Combine like terms: 9 + -9 = 0
0 + 16x + x2 = 0 + -9
16x + x2 = 0 + -9

Combine like terms: 0 + -9 = -9
16x + x2 = -9

The x term is 16x.  Take half its coefficient (8).
Square it (64) and add it to both sides.

Add '64' to each side of the equation.
16x + 64 + x2 = -9 + 64

Reorder the terms:
64 + 16x + x2 = -9 + 64

Combine like terms: -9 + 64 = 55
64 + 16x + x2 = 55

Factor a perfect square on the left side:
(x + 8)(x + 8) = 55

Calculate the square root of the right side: 7.416198487

Break this problem into two subproblems by setting 
(x + 8) equal to 7.416198487 and -7.416198487.

Subproblem 1

x + 8 = 7.416198487 Simplifying x + 8 = 7.416198487 Reorder the terms: 8 + x = 7.416198487 Solving 8 + x = 7.416198487 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-8' to each side of the equation. 8 + -8 + x = 7.416198487 + -8 Combine like terms: 8 + -8 = 0 0 + x = 7.416198487 + -8 x = 7.416198487 + -8 Combine like terms: 7.416198487 + -8 = -0.583801513 x = -0.583801513 Simplifying x = -0.583801513

Subproblem 2

x + 8 = -7.416198487 Simplifying x + 8 = -7.416198487 Reorder the terms: 8 + x = -7.416198487 Solving 8 + x = -7.416198487 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-8' to each side of the equation. 8 + -8 + x = -7.416198487 + -8 Combine like terms: 8 + -8 = 0 0 + x = -7.416198487 + -8 x = -7.416198487 + -8 Combine like terms: -7.416198487 + -8 = -15.416198487 x = -15.416198487 Simplifying x = -15.416198487

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-0.583801513, -15.416198487}

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