3x(x+5)=39

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Solution for 3x(x+5)=39 equation: 


Simplifying
3x(x + 5) = 39

Reorder the terms:
3x(5 + x) = 39
(5 * 3x + x * 3x) = 39
(15x + 3x2) = 39

Solving
15x + 3x2 = 39

Solving for variable 'x'.

Reorder the terms:
-39 + 15x + 3x2 = 39 + -39

Combine like terms: 39 + -39 = 0
-39 + 15x + 3x2 = 0

Factor out the Greatest Common Factor (GCF), '3'.
3(-13 + 5x + x2) = 0

Ignore the factor 3.

Subproblem 1
Set the factor '(-13 + 5x + x2)' equal to zero and attempt to solve:

Simplifying
-13 + 5x + x2 = 0

Solving
-13 + 5x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '13' to each side of the equation.
-13 + 5x + 13 + x2 = 0 + 13

Reorder the terms:
-13 + 13 + 5x + x2 = 0 + 13

Combine like terms: -13 + 13 = 0
0 + 5x + x2 = 0 + 13
5x + x2 = 0 + 13

Combine like terms: 0 + 13 = 13
5x + x2 = 13

The x term is 5x.  Take half its coefficient (2.5).
Square it (6.25) and add it to both sides.

Add '6.25' to each side of the equation.
5x + 6.25 + x2 = 13 + 6.25

Reorder the terms:
6.25 + 5x + x2 = 13 + 6.25

Combine like terms: 13 + 6.25 = 19.25
6.25 + 5x + x2 = 19.25

Factor a perfect square on the left side:
(x + 2.5)(x + 2.5) = 19.25

Calculate the square root of the right side: 4.387482194

Break this problem into two subproblems by setting 
(x + 2.5) equal to 4.387482194 and -4.387482194.


Subproblem 1
x + 2.5 = 4.387482194

Simplifying
x + 2.5 = 4.387482194

Reorder the terms:
2.5 + x = 4.387482194

Solving
2.5 + x = 4.387482194

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '-2.5' to each side of the equation.
2.5 + -2.5 + x = 4.387482194 + -2.5

Combine like terms: 2.5 + -2.5 = 0.0
0.0 + x = 4.387482194 + -2.5
x = 4.387482194 + -2.5

Combine like terms: 4.387482194 + -2.5 = 1.887482194
x = 1.887482194

Simplifying
x = 1.887482194


Subproblem 2
x + 2.5 = -4.387482194

Simplifying
x + 2.5 = -4.387482194

Reorder the terms:
2.5 + x = -4.387482194

Solving
2.5 + x = -4.387482194

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '-2.5' to each side of the equation.
2.5 + -2.5 + x = -4.387482194 + -2.5

Combine like terms: 2.5 + -2.5 = 0.0
0.0 + x = -4.387482194 + -2.5
x = -4.387482194 + -2.5

Combine like terms: -4.387482194 + -2.5 = -6.887482194
x = -6.887482194

Simplifying
x = -6.887482194


Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {1.887482194, -6.887482194}
Solution
x = {1.887482194, -6.887482194}

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