y=y^2-20

Solution for y=y^2-20 equation:

Simplifying
y = y2 + -20

Reorder the terms:
y = -20 + y2

Solving
y = -20 + y2

Solving for variable 'y'.

Reorder the terms:
20 + y + -1y2 = -20 + y2 + 20 + -1y2

Reorder the terms:
20 + y + -1y2 = -20 + 20 + y2 + -1y2

Combine like terms: -20 + 20 = 0
20 + y + -1y2 = 0 + y2 + -1y2
20 + y + -1y2 = y2 + -1y2

Combine like terms: y2 + -1y2 = 0
20 + y + -1y2 = 0

Factor a trinomial.
(5 + -1y)(4 + y) = 0

Subproblem 1
Set the factor '(5 + -1y)' equal to zero and attempt to solve:

Simplifying
5 + -1y = 0

Solving
5 + -1y = 0

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

Add '-5' to each side of the equation.
5 + -5 + -1y = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -1y = 0 + -5
-1y = 0 + -5

Combine like terms: 0 + -5 = -5
-1y = -5

Divide each side by '-1'.
y = 5

Simplifying
y = 5
Subproblem 2
Set the factor '(4 + y)' equal to zero and attempt to solve:

Simplifying
4 + y = 0

Solving
4 + y = 0

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

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

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

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

Simplifying
y = -4
Solution
y = {5, -4}