5x+7=3x(x+9)-20

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Solution for 5x+7=3x(x+9)-20 equation:


Simplifying
5x + 7 = 3x(x + 9) + -20

Reorder the terms:
7 + 5x = 3x(x + 9) + -20

Reorder the terms:
7 + 5x = 3x(9 + x) + -20
7 + 5x = (9 * 3x + x * 3x) + -20
7 + 5x = (27x + 3x2) + -20

Reorder the terms:
7 + 5x = -20 + 27x + 3x2

Solving
7 + 5x = -20 + 27x + 3x2

Solving for variable 'x'.

Reorder the terms:
7 + 20 + 5x + -27x + -3x2 = -20 + 27x + 3x2 + 20 + -27x + -3x2

Combine like terms: 7 + 20 = 27
27 + 5x + -27x + -3x2 = -20 + 27x + 3x2 + 20 + -27x + -3x2

Combine like terms: 5x + -27x = -22x
27 + -22x + -3x2 = -20 + 27x + 3x2 + 20 + -27x + -3x2

Reorder the terms:
27 + -22x + -3x2 = -20 + 20 + 27x + -27x + 3x2 + -3x2

Combine like terms: -20 + 20 = 0
27 + -22x + -3x2 = 0 + 27x + -27x + 3x2 + -3x2
27 + -22x + -3x2 = 27x + -27x + 3x2 + -3x2

Combine like terms: 27x + -27x = 0
27 + -22x + -3x2 = 0 + 3x2 + -3x2
27 + -22x + -3x2 = 3x2 + -3x2

Combine like terms: 3x2 + -3x2 = 0
27 + -22x + -3x2 = 0

Begin completing the square.  Divide all terms by
-3 the coefficient of the squared term: 

Divide each side by '-3'.
-9 + 7.333333333x + x2 = 0

Move the constant term to the right:

Add '9' to each side of the equation.
-9 + 7.333333333x + 9 + x2 = 0 + 9

Reorder the terms:
-9 + 9 + 7.333333333x + x2 = 0 + 9

Combine like terms: -9 + 9 = 0
0 + 7.333333333x + x2 = 0 + 9
7.333333333x + x2 = 0 + 9

Combine like terms: 0 + 9 = 9
7.333333333x + x2 = 9

The x term is 7.333333333x.  Take half its coefficient (3.666666667).
Square it (13.44444445) and add it to both sides.

Add '13.44444445' to each side of the equation.
7.333333333x + 13.44444445 + x2 = 9 + 13.44444445

Reorder the terms:
13.44444445 + 7.333333333x + x2 = 9 + 13.44444445

Combine like terms: 9 + 13.44444445 = 22.44444445
13.44444445 + 7.333333333x + x2 = 22.44444445

Factor a perfect square on the left side:
(x + 3.666666667)(x + 3.666666667) = 22.44444445

Calculate the square root of the right side: 4.737556802

Break this problem into two subproblems by setting 
(x + 3.666666667) equal to 4.737556802 and -4.737556802.

Subproblem 1

x + 3.666666667 = 4.737556802 Simplifying x + 3.666666667 = 4.737556802 Reorder the terms: 3.666666667 + x = 4.737556802 Solving 3.666666667 + x = 4.737556802 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.666666667' to each side of the equation. 3.666666667 + -3.666666667 + x = 4.737556802 + -3.666666667 Combine like terms: 3.666666667 + -3.666666667 = 0.000000000 0.000000000 + x = 4.737556802 + -3.666666667 x = 4.737556802 + -3.666666667 Combine like terms: 4.737556802 + -3.666666667 = 1.070890135 x = 1.070890135 Simplifying x = 1.070890135

Subproblem 2

x + 3.666666667 = -4.737556802 Simplifying x + 3.666666667 = -4.737556802 Reorder the terms: 3.666666667 + x = -4.737556802 Solving 3.666666667 + x = -4.737556802 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.666666667' to each side of the equation. 3.666666667 + -3.666666667 + x = -4.737556802 + -3.666666667 Combine like terms: 3.666666667 + -3.666666667 = 0.000000000 0.000000000 + x = -4.737556802 + -3.666666667 x = -4.737556802 + -3.666666667 Combine like terms: -4.737556802 + -3.666666667 = -8.404223469 x = -8.404223469 Simplifying x = -8.404223469

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.070890135, -8.404223469}

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