=3(x-3.8)(x+1.2)

Solution for =3(x-3.8)(x+1.2) equation:

Simplifying
0 = 3(x + -3.8)(x + 1.2)

Reorder the terms:
0 = 3(-3.8 + x)(x + 1.2)

Reorder the terms:
0 = 3(-3.8 + x)(1.2 + x)

Multiply (-3.8 + x) * (1.2 + x)
0 = 3(-3.8(1.2 + x) + x(1.2 + x))
0 = 3((1.2 * -3.8 + x * -3.8) + x(1.2 + x))
0 = 3((-4.56 + -3.8x) + x(1.2 + x))
0 = 3(-4.56 + -3.8x + (1.2 * x + x * x))
0 = 3(-4.56 + -3.8x + (1.2x + x2))

Combine like terms: -3.8x + 1.2x = -2.6x
0 = 3(-4.56 + -2.6x + x2)
0 = (-4.56 * 3 + -2.6x * 3 + x2 * 3)
0 = (-13.68 + -7.8x + 3x2)

Solving
0 = -13.68 + -7.8x + 3x2

Solving for variable 'x'.

Combine like terms: 0 + 13.68 = 13.68
13.68 + 7.8x + -3x2 = -13.68 + -7.8x + 3x2 + 13.68 + 7.8x + -3x2

Reorder the terms:
13.68 + 7.8x + -3x2 = -13.68 + 13.68 + -7.8x + 7.8x + 3x2 + -3x2

Combine like terms: -13.68 + 13.68 = 0.00
13.68 + 7.8x + -3x2 = 0.00 + -7.8x + 7.8x + 3x2 + -3x2
13.68 + 7.8x + -3x2 = -7.8x + 7.8x + 3x2 + -3x2

Combine like terms: -7.8x + 7.8x = 0.0
13.68 + 7.8x + -3x2 = 0.0 + 3x2 + -3x2
13.68 + 7.8x + -3x2 = 3x2 + -3x2

Combine like terms: 3x2 + -3x2 = 0
13.68 + 7.8x + -3x2 = 0

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

Divide each side by '-3'.
-4.56 + -2.6x + x2 = 0

Move the constant term to the right:

Add '4.56' to each side of the equation.
-4.56 + -2.6x + 4.56 + x2 = 0 + 4.56

Reorder the terms:
-4.56 + 4.56 + -2.6x + x2 = 0 + 4.56

Combine like terms: -4.56 + 4.56 = 0.00
0.00 + -2.6x + x2 = 0 + 4.56
-2.6x + x2 = 0 + 4.56

Combine like terms: 0 + 4.56 = 4.56
-2.6x + x2 = 4.56

The x term is -2.6x.  Take half its coefficient (-1.3).
Square it (1.69) and add it to both sides.

Add '1.69' to each side of the equation.
-2.6x + 1.69 + x2 = 4.56 + 1.69

Reorder the terms:
1.69 + -2.6x + x2 = 4.56 + 1.69

Combine like terms: 4.56 + 1.69 = 6.25
1.69 + -2.6x + x2 = 6.25

Factor a perfect square on the left side:
(x + -1.3)(x + -1.3) = 6.25

Calculate the square root of the right side: 2.5

Break this problem into two subproblems by setting 
(x + -1.3) equal to 2.5 and -2.5.

Subproblem 1
x + -1.3 = 2.5

Simplifying
x + -1.3 = 2.5

Reorder the terms:
-1.3 + x = 2.5

Solving
-1.3 + x = 2.5

Solving for variable 'x'.

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

Add '1.3' to each side of the equation.
-1.3 + 1.3 + x = 2.5 + 1.3

Combine like terms: -1.3 + 1.3 = 0.0
0.0 + x = 2.5 + 1.3
x = 2.5 + 1.3

Combine like terms: 2.5 + 1.3 = 3.8
x = 3.8

Simplifying
x = 3.8

Subproblem 2
x + -1.3 = -2.5

Simplifying
x + -1.3 = -2.5

Reorder the terms:
-1.3 + x = -2.5

Solving
-1.3 + x = -2.5

Solving for variable 'x'.

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

Add '1.3' to each side of the equation.
-1.3 + 1.3 + x = -2.5 + 1.3

Combine like terms: -1.3 + 1.3 = 0.0
0.0 + x = -2.5 + 1.3
x = -2.5 + 1.3

Combine like terms: -2.5 + 1.3 = -1.2
x = -1.2

Simplifying
x = -1.2

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {3.8, -1.2}