(x+2.8)(x+1.3)=0

Solution for (x+2.8)(x+1.3)=0 equation:

Simplifying
(x + 2.8)(x + 1.3) = 0

Reorder the terms:
(2.8 + x)(x + 1.3) = 0

Reorder the terms:
(2.8 + x)(1.3 + x) = 0

Multiply (2.8 + x) * (1.3 + x)
(2.8(1.3 + x) + x(1.3 + x)) = 0
((1.3 * 2.8 + x * 2.8) + x(1.3 + x)) = 0
((3.64 + 2.8x) + x(1.3 + x)) = 0
(3.64 + 2.8x + (1.3 * x + x * x)) = 0
(3.64 + 2.8x + (1.3x + x2)) = 0

Combine like terms: 2.8x + 1.3x = 4.1x
(3.64 + 4.1x + x2) = 0

Solving
3.64 + 4.1x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-3.64' to each side of the equation.
3.64 + 4.1x + -3.64 + x2 = 0 + -3.64

Reorder the terms:
3.64 + -3.64 + 4.1x + x2 = 0 + -3.64

Combine like terms: 3.64 + -3.64 = 0.00
0.00 + 4.1x + x2 = 0 + -3.64
4.1x + x2 = 0 + -3.64

Combine like terms: 0 + -3.64 = -3.64
4.1x + x2 = -3.64

The x term is 4.1x.  Take half its coefficient (2.05).
Square it (4.2025) and add it to both sides.

Add '4.2025' to each side of the equation.
4.1x + 4.2025 + x2 = -3.64 + 4.2025

Reorder the terms:
4.2025 + 4.1x + x2 = -3.64 + 4.2025

Combine like terms: -3.64 + 4.2025 = 0.5625
4.2025 + 4.1x + x2 = 0.5625

Factor a perfect square on the left side:
(x + 2.05)(x + 2.05) = 0.5625

Calculate the square root of the right side: 0.75

Break this problem into two subproblems by setting 
(x + 2.05) equal to 0.75 and -0.75.

Subproblem 1
x + 2.05 = 0.75

Simplifying
x + 2.05 = 0.75

Reorder the terms:
2.05 + x = 0.75

Solving
2.05 + x = 0.75

Solving for variable 'x'.

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

Add '-2.05' to each side of the equation.
2.05 + -2.05 + x = 0.75 + -2.05

Combine like terms: 2.05 + -2.05 = 0.00
0.00 + x = 0.75 + -2.05
x = 0.75 + -2.05

Combine like terms: 0.75 + -2.05 = -1.3
x = -1.3

Simplifying
x = -1.3

Subproblem 2
x + 2.05 = -0.75

Simplifying
x + 2.05 = -0.75

Reorder the terms:
2.05 + x = -0.75

Solving
2.05 + x = -0.75

Solving for variable 'x'.

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

Add '-2.05' to each side of the equation.
2.05 + -2.05 + x = -0.75 + -2.05

Combine like terms: 2.05 + -2.05 = 0.00
0.00 + x = -0.75 + -2.05
x = -0.75 + -2.05

Combine like terms: -0.75 + -2.05 = -2.8
x = -2.8

Simplifying
x = -2.8

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {-1.3, -2.8}