2x^2-4x=10.4

Solution for 2x^2-4x=10.4 equation:

Simplifying
2x2 + -4x = 10.4

Reorder the terms:
-4x + 2x2 = 10.4

Solving
-4x + 2x2 = 10.4

Solving for variable 'x'.

Reorder the terms:
-10.4 + -4x + 2x2 = 10.4 + -10.4

Combine like terms: 10.4 + -10.4 = 0.0
-10.4 + -4x + 2x2 = 0.0

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

Divide each side by '2'.
-5.2 + -2x + x2 = 0.0

Move the constant term to the right:

Add '5.2' to each side of the equation.
-5.2 + -2x + 5.2 + x2 = 0.0 + 5.2

Reorder the terms:
-5.2 + 5.2 + -2x + x2 = 0.0 + 5.2

Combine like terms: -5.2 + 5.2 = 0.0
0.0 + -2x + x2 = 0.0 + 5.2
-2x + x2 = 0.0 + 5.2

Combine like terms: 0.0 + 5.2 = 5.2
-2x + x2 = 5.2

The x term is -2x.  Take half its coefficient (-1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
-2x + 1 + x2 = 5.2 + 1

Reorder the terms:
1 + -2x + x2 = 5.2 + 1

Combine like terms: 5.2 + 1 = 6.2
1 + -2x + x2 = 6.2

Factor a perfect square on the left side:
(x + -1)(x + -1) = 6.2

Calculate the square root of the right side: 2.48997992

Break this problem into two subproblems by setting 
(x + -1) equal to 2.48997992 and -2.48997992.

Subproblem 1
x + -1 = 2.48997992

Simplifying
x + -1 = 2.48997992

Reorder the terms:
-1 + x = 2.48997992

Solving
-1 + x = 2.48997992

Solving for variable 'x'.

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

Add '1' to each side of the equation.
-1 + 1 + x = 2.48997992 + 1

Combine like terms: -1 + 1 = 0
0 + x = 2.48997992 + 1
x = 2.48997992 + 1

Combine like terms: 2.48997992 + 1 = 3.48997992
x = 3.48997992

Simplifying
x = 3.48997992

Subproblem 2
x + -1 = -2.48997992

Simplifying
x + -1 = -2.48997992

Reorder the terms:
-1 + x = -2.48997992

Solving
-1 + x = -2.48997992

Solving for variable 'x'.

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

Add '1' to each side of the equation.
-1 + 1 + x = -2.48997992 + 1

Combine like terms: -1 + 1 = 0
0 + x = -2.48997992 + 1
x = -2.48997992 + 1

Combine like terms: -2.48997992 + 1 = -1.48997992
x = -1.48997992

Simplifying
x = -1.48997992

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {3.48997992, -1.48997992}