y^2+2y-4=0

Solution for y^2+2y-4=0 equation:

Simplifying
y2 + 2y + -4 = 0

Reorder the terms:
-4 + 2y + y2 = 0

Solving
-4 + 2y + y2 = 0

Solving for variable 'y'.

Begin completing the square.

Move the constant term to the right:

Add '4' to each side of the equation.
-4 + 2y + 4 + y2 = 0 + 4

Reorder the terms:
-4 + 4 + 2y + y2 = 0 + 4

Combine like terms: -4 + 4 = 0
0 + 2y + y2 = 0 + 4
2y + y2 = 0 + 4

Combine like terms: 0 + 4 = 4
2y + y2 = 4

The y term is 2y.  Take half its coefficient (1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
2y + 1 + y2 = 4 + 1

Reorder the terms:
1 + 2y + y2 = 4 + 1

Combine like terms: 4 + 1 = 5
1 + 2y + y2 = 5

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

Calculate the square root of the right side: 2.236067978

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

Subproblem 1
y + 1 = 2.236067978

Simplifying
y + 1 = 2.236067978

Reorder the terms:
1 + y = 2.236067978

Solving
1 + y = 2.236067978

Solving for variable 'y'.

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

Add '-1' to each side of the equation.
1 + -1 + y = 2.236067978 + -1

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

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

Simplifying
y = 1.236067978

Subproblem 2
y + 1 = -2.236067978

Simplifying
y + 1 = -2.236067978

Reorder the terms:
1 + y = -2.236067978

Solving
1 + y = -2.236067978

Solving for variable 'y'.

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

Add '-1' to each side of the equation.
1 + -1 + y = -2.236067978 + -1

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

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

Simplifying
y = -3.236067978

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