3(x+1)(x+1)=15

Solution for 3(x+1)(x+1)=15 equation:

Simplifying
3(x + 1)(x + 1) = 15

Reorder the terms:
3(1 + x)(x + 1) = 15

Reorder the terms:
3(1 + x)(1 + x) = 15

Multiply (1 + x) * (1 + x)
3(1(1 + x) + x(1 + x)) = 15
3((1 * 1 + x * 1) + x(1 + x)) = 15
3((1 + 1x) + x(1 + x)) = 15
3(1 + 1x + (1 * x + x * x)) = 15
3(1 + 1x + (1x + x2)) = 15

Combine like terms: 1x + 1x = 2x
3(1 + 2x + x2) = 15
(1 * 3 + 2x * 3 + x2 * 3) = 15
(3 + 6x + 3x2) = 15

Solving
3 + 6x + 3x2 = 15

Solving for variable 'x'.

Reorder the terms:
3 + -15 + 6x + 3x2 = 15 + -15

Combine like terms: 3 + -15 = -12
-12 + 6x + 3x2 = 15 + -15

Combine like terms: 15 + -15 = 0
-12 + 6x + 3x2 = 0

Factor out the Greatest Common Factor (GCF), '3'.
3(-4 + 2x + x2) = 0

Ignore the factor 3.
Subproblem 1
Set the factor '(-4 + 2x + x2)' equal to zero and attempt to solve:

Simplifying
-4 + 2x + x2 = 0

Solving
-4 + 2x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '4' to each side of the equation.
-4 + 2x + 4 + x2 = 0 + 4

Reorder the terms:
-4 + 4 + 2x + x2 = 0 + 4

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

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

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 = 4 + 1

Reorder the terms:
1 + 2x + x2 = 4 + 1

Combine like terms: 4 + 1 = 5
1 + 2x + x2 = 5

Factor a perfect square on the left side:
(x + 1)(x + 1) = 5

Calculate the square root of the right side: 2.236067978

Break this problem into two subproblems by setting 
(x + 1) equal to 2.236067978 and -2.236067978.

Subproblem 1
x + 1 = 2.236067978

Simplifying
x + 1 = 2.236067978

Reorder the terms:
1 + x = 2.236067978

Solving
1 + x = 2.236067978

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 = 2.236067978 + -1

Combine like terms: 1 + -1 = 0
0 + x = 2.236067978 + -1
x = 2.236067978 + -1

Combine like terms: 2.236067978 + -1 = 1.236067978
x = 1.236067978

Simplifying
x = 1.236067978

Subproblem 2
x + 1 = -2.236067978

Simplifying
x + 1 = -2.236067978

Reorder the terms:
1 + x = -2.236067978

Solving
1 + x = -2.236067978

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 = -2.236067978 + -1

Combine like terms: 1 + -1 = 0
0 + x = -2.236067978 + -1
x = -2.236067978 + -1

Combine like terms: -2.236067978 + -1 = -3.236067978
x = -3.236067978

Simplifying
x = -3.236067978

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {1.236067978, -3.236067978}
Solution
x = {1.236067978, -3.236067978}