28x+(4x*4x)=72

Solution for 28x+(4x*4x)=72 equation:

Simplifying
28x + (4x * 4x) = 72

Reorder the terms for easier multiplication:
28x + (4 * 4x * x) = 72

Multiply 4 * 4
28x + (16x * x) = 72

Multiply x * x
28x + (16x2) = 72

Solving
28x + (16x2) = 72

Solving for variable 'x'.

Reorder the terms:
-72 + 28x + (16x2) = 72 + -72

Combine like terms: 72 + -72 = 0
-72 + 28x + (16x2) = 0

Factor out the Greatest Common Factor (GCF), '4'.
4(-18 + 7x + (4x2)) = 0

Ignore the factor 4.
Subproblem 1
Set the factor '(-18 + 7x + (4x2))' equal to zero and attempt to solve:

Simplifying
-18 + 7x + (4x2) = 0

Solving
-18 + 7x + (4x2) = 0

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

Divide each side by '4'.
-4.5 + 1.75x + x2 = 0

Move the constant term to the right:

Add '4.5' to each side of the equation.
-4.5 + 1.75x + 4.5 + x2 = 0 + 4.5

Reorder the terms:
-4.5 + 4.5 + 1.75x + x2 = 0 + 4.5

Combine like terms: -4.5 + 4.5 = 0.0
0.0 + 1.75x + x2 = 0 + 4.5
1.75x + x2 = 0 + 4.5

Combine like terms: 0 + 4.5 = 4.5
1.75x + x2 = 4.5

The x term is 1.75x.  Take half its coefficient (0.875).
Square it (0.765625) and add it to both sides.

Add '0.765625' to each side of the equation.
1.75x + 0.765625 + x2 = 4.5 + 0.765625

Reorder the terms:
0.765625 + 1.75x + x2 = 4.5 + 0.765625

Combine like terms: 4.5 + 0.765625 = 5.265625
0.765625 + 1.75x + x2 = 5.265625

Factor a perfect square on the left side:
((x) + 0.875)((x) + 0.875) = 5.265625

Calculate the square root of the right side: 2.294694969

Break this problem into two subproblems by setting 
((x) + 0.875) equal to 2.294694969 and -2.294694969.

Subproblem 1
(x) + 0.875 = 2.294694969

Simplifying
(x) + 0.875 = 2.294694969
x + 0.875 = 2.294694969

Reorder the terms:
0.875 + x = 2.294694969

Solving
0.875 + x = 2.294694969

Solving for variable 'x'.

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

Add '-0.875' to each side of the equation.
0.875 + -0.875 + x = 2.294694969 + -0.875

Combine like terms: 0.875 + -0.875 = 0.000
0.000 + x = 2.294694969 + -0.875
x = 2.294694969 + -0.875

Combine like terms: 2.294694969 + -0.875 = 1.419694969
x = 1.419694969

Simplifying
x = 1.419694969

Subproblem 2
(x) + 0.875 = -2.294694969

Simplifying
(x) + 0.875 = -2.294694969
x + 0.875 = -2.294694969

Reorder the terms:
0.875 + x = -2.294694969

Solving
0.875 + x = -2.294694969

Solving for variable 'x'.

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

Add '-0.875' to each side of the equation.
0.875 + -0.875 + x = -2.294694969 + -0.875

Combine like terms: 0.875 + -0.875 = 0.000
0.000 + x = -2.294694969 + -0.875
x = -2.294694969 + -0.875

Combine like terms: -2.294694969 + -0.875 = -3.169694969
x = -3.169694969

Simplifying
x = -3.169694969

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {1.419694969, -3.169694969}
Solution
x = {1.419694969, -3.169694969}