400=2(3.14)(x*x)+2(3.14)(x)(40)

Solution for 400=2(3.14)(x*x)+2(3.14)(x)(40) equation:

Simplifying
400 = 2(3.14)(x * x) + 2(3.14)(x)(40)

Multiply x * x
400 = 2 * 3.14(x2) + 2(3.14)(x)(40)

Multiply 2 * 3.14
400 = 6.28x2 + 2(3.14)(x)(40)

Reorder the terms for easier multiplication:
400 = 6.28x2 + 2 * 3.14 * 40x

Multiply 2 * 3.14
400 = 6.28x2 + 6.28 * 40x

Multiply 6.28 * 40
400 = 6.28x2 + 251.2x

Reorder the terms:
400 = 251.2x + 6.28x2

Solving
400 = 251.2x + 6.28x2

Solving for variable 'x'.

Reorder the terms:
400 + -251.2x + -6.28x2 = 251.2x + -251.2x + 6.28x2 + -6.28x2

Combine like terms: 251.2x + -251.2x = 0.0
400 + -251.2x + -6.28x2 = 0.0 + 6.28x2 + -6.28x2
400 + -251.2x + -6.28x2 = 6.28x2 + -6.28x2

Combine like terms: 6.28x2 + -6.28x2 = 0.00
400 + -251.2x + -6.28x2 = 0.00

Begin completing the square.  Divide all terms by
-6.28 the coefficient of the squared term: 

Divide each side by '-6.28'.
-63.69426752 + 40x + x2 = 0

Move the constant term to the right:

Add '63.69426752' to each side of the equation.
-63.69426752 + 40x + 63.69426752 + x2 = 0 + 63.69426752

Reorder the terms:
-63.69426752 + 63.69426752 + 40x + x2 = 0 + 63.69426752

Combine like terms: -63.69426752 + 63.69426752 = 0.00000000
0.00000000 + 40x + x2 = 0 + 63.69426752
40x + x2 = 0 + 63.69426752

Combine like terms: 0 + 63.69426752 = 63.69426752
40x + x2 = 63.69426752

The x term is 40x.  Take half its coefficient (20).
Square it (400) and add it to both sides.

Add '400' to each side of the equation.
40x + 400 + x2 = 63.69426752 + 400

Reorder the terms:
400 + 40x + x2 = 63.69426752 + 400

Combine like terms: 63.69426752 + 400 = 463.69426752
400 + 40x + x2 = 463.69426752

Factor a perfect square on the left side:
(x + 20)(x + 20) = 463.69426752

Calculate the square root of the right side: 21.533561422

Break this problem into two subproblems by setting 
(x + 20) equal to 21.533561422 and -21.533561422.

Subproblem 1
x + 20 = 21.533561422

Simplifying
x + 20 = 21.533561422

Reorder the terms:
20 + x = 21.533561422

Solving
20 + x = 21.533561422

Solving for variable 'x'.

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

Add '-20' to each side of the equation.
20 + -20 + x = 21.533561422 + -20

Combine like terms: 20 + -20 = 0
0 + x = 21.533561422 + -20
x = 21.533561422 + -20

Combine like terms: 21.533561422 + -20 = 1.533561422
x = 1.533561422

Simplifying
x = 1.533561422

Subproblem 2
x + 20 = -21.533561422

Simplifying
x + 20 = -21.533561422

Reorder the terms:
20 + x = -21.533561422

Solving
20 + x = -21.533561422

Solving for variable 'x'.

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

Add '-20' to each side of the equation.
20 + -20 + x = -21.533561422 + -20

Combine like terms: 20 + -20 = 0
0 + x = -21.533561422 + -20
x = -21.533561422 + -20

Combine like terms: -21.533561422 + -20 = -41.533561422
x = -41.533561422

Simplifying
x = -41.533561422

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {1.533561422, -41.533561422}