2.62=(0.85-2x)(0.15-2x)

Solution for 2.62=(0.85-2x)(0.15-2x) equation:

Simplifying
2.62 = (0.85 + -2x)(0.15 + -2x)

Multiply (0.85 + -2x) * (0.15 + -2x)
2.62 = (0.85(0.15 + -2x) + -2x * (0.15 + -2x))
2.62 = ((0.15 * 0.85 + -2x * 0.85) + -2x * (0.15 + -2x))
2.62 = ((0.1275 + -1.7x) + -2x * (0.15 + -2x))
2.62 = (0.1275 + -1.7x + (0.15 * -2x + -2x * -2x))
2.62 = (0.1275 + -1.7x + (-0.3x + 4x2))

Combine like terms: -1.7x + -0.3x = -2x
2.62 = (0.1275 + -2x + 4x2)

Solving
2.62 = 0.1275 + -2x + 4x2

Solving for variable 'x'.

Combine like terms: 2.62 + -0.1275 = 2.4925
2.4925 + 2x + -4x2 = 0.1275 + -2x + 4x2 + -0.1275 + 2x + -4x2

Reorder the terms:
2.4925 + 2x + -4x2 = 0.1275 + -0.1275 + -2x + 2x + 4x2 + -4x2

Combine like terms: 0.1275 + -0.1275 = 0.0000
2.4925 + 2x + -4x2 = 0.0000 + -2x + 2x + 4x2 + -4x2
2.4925 + 2x + -4x2 = -2x + 2x + 4x2 + -4x2

Combine like terms: -2x + 2x = 0
2.4925 + 2x + -4x2 = 0 + 4x2 + -4x2
2.4925 + 2x + -4x2 = 4x2 + -4x2

Combine like terms: 4x2 + -4x2 = 0
2.4925 + 2x + -4x2 = 0

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

Divide each side by '-4'.
-0.623125 + -0.5x + x2 = 0

Move the constant term to the right:

Add '0.623125' to each side of the equation.
-0.623125 + -0.5x + 0.623125 + x2 = 0 + 0.623125

Reorder the terms:
-0.623125 + 0.623125 + -0.5x + x2 = 0 + 0.623125

Combine like terms: -0.623125 + 0.623125 = 0.000000
0.000000 + -0.5x + x2 = 0 + 0.623125
-0.5x + x2 = 0 + 0.623125

Combine like terms: 0 + 0.623125 = 0.623125
-0.5x + x2 = 0.623125

The x term is -0.5x.  Take half its coefficient (-0.25).
Square it (0.0625) and add it to both sides.

Add '0.0625' to each side of the equation.
-0.5x + 0.0625 + x2 = 0.623125 + 0.0625

Reorder the terms:
0.0625 + -0.5x + x2 = 0.623125 + 0.0625

Combine like terms: 0.623125 + 0.0625 = 0.685625
0.0625 + -0.5x + x2 = 0.685625

Factor a perfect square on the left side:
(x + -0.25)(x + -0.25) = 0.685625

Calculate the square root of the right side: 0.828024758

Break this problem into two subproblems by setting 
(x + -0.25) equal to 0.828024758 and -0.828024758.

Subproblem 1
x + -0.25 = 0.828024758

Simplifying
x + -0.25 = 0.828024758

Reorder the terms:
-0.25 + x = 0.828024758

Solving
-0.25 + x = 0.828024758

Solving for variable 'x'.

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

Add '0.25' to each side of the equation.
-0.25 + 0.25 + x = 0.828024758 + 0.25

Combine like terms: -0.25 + 0.25 = 0.00
0.00 + x = 0.828024758 + 0.25
x = 0.828024758 + 0.25

Combine like terms: 0.828024758 + 0.25 = 1.078024758
x = 1.078024758

Simplifying
x = 1.078024758

Subproblem 2
x + -0.25 = -0.828024758

Simplifying
x + -0.25 = -0.828024758

Reorder the terms:
-0.25 + x = -0.828024758

Solving
-0.25 + x = -0.828024758

Solving for variable 'x'.

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

Add '0.25' to each side of the equation.
-0.25 + 0.25 + x = -0.828024758 + 0.25

Combine like terms: -0.25 + 0.25 = 0.00
0.00 + x = -0.828024758 + 0.25
x = -0.828024758 + 0.25

Combine like terms: -0.828024758 + 0.25 = -0.578024758
x = -0.578024758

Simplifying
x = -0.578024758

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {1.078024758, -0.578024758}