7x(x+9)=-8

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Solution for 7x(x+9)=-8 equation:


Simplifying
7x(x + 9) = -8

Reorder the terms:
7x(9 + x) = -8
(9 * 7x + x * 7x) = -8
(63x + 7x2) = -8

Solving
63x + 7x2 = -8

Solving for variable 'x'.

Reorder the terms:
8 + 63x + 7x2 = -8 + 8

Combine like terms: -8 + 8 = 0
8 + 63x + 7x2 = 0

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

Divide each side by '7'.
1.142857143 + 9x + x2 = 0

Move the constant term to the right:

Add '-1.142857143' to each side of the equation.
1.142857143 + 9x + -1.142857143 + x2 = 0 + -1.142857143

Reorder the terms:
1.142857143 + -1.142857143 + 9x + x2 = 0 + -1.142857143

Combine like terms: 1.142857143 + -1.142857143 = 0.000000000
0.000000000 + 9x + x2 = 0 + -1.142857143
9x + x2 = 0 + -1.142857143

Combine like terms: 0 + -1.142857143 = -1.142857143
9x + x2 = -1.142857143

The x term is 9x.  Take half its coefficient (4.5).
Square it (20.25) and add it to both sides.

Add '20.25' to each side of the equation.
9x + 20.25 + x2 = -1.142857143 + 20.25

Reorder the terms:
20.25 + 9x + x2 = -1.142857143 + 20.25

Combine like terms: -1.142857143 + 20.25 = 19.107142857
20.25 + 9x + x2 = 19.107142857

Factor a perfect square on the left side:
(x + 4.5)(x + 4.5) = 19.107142857

Calculate the square root of the right side: 4.371171794

Break this problem into two subproblems by setting 
(x + 4.5) equal to 4.371171794 and -4.371171794.

Subproblem 1

x + 4.5 = 4.371171794 Simplifying x + 4.5 = 4.371171794 Reorder the terms: 4.5 + x = 4.371171794 Solving 4.5 + x = 4.371171794 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-4.5' to each side of the equation. 4.5 + -4.5 + x = 4.371171794 + -4.5 Combine like terms: 4.5 + -4.5 = 0.0 0.0 + x = 4.371171794 + -4.5 x = 4.371171794 + -4.5 Combine like terms: 4.371171794 + -4.5 = -0.128828206 x = -0.128828206 Simplifying x = -0.128828206

Subproblem 2

x + 4.5 = -4.371171794 Simplifying x + 4.5 = -4.371171794 Reorder the terms: 4.5 + x = -4.371171794 Solving 4.5 + x = -4.371171794 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-4.5' to each side of the equation. 4.5 + -4.5 + x = -4.371171794 + -4.5 Combine like terms: 4.5 + -4.5 = 0.0 0.0 + x = -4.371171794 + -4.5 x = -4.371171794 + -4.5 Combine like terms: -4.371171794 + -4.5 = -8.871171794 x = -8.871171794 Simplifying x = -8.871171794

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-0.128828206, -8.871171794}

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