y(y-1)=20

Solution for y(y-1)=20 equation:

Simplifying
y(y + -1) = 20

Reorder the terms:
y(-1 + y) = 20
(-1 * y + y * y) = 20
(-1y + y2) = 20

Solving
-1y + y2 = 20

Solving for variable 'y'.

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

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

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

Subproblem 1
Set the factor '(-4 + -1y)' equal to zero and attempt to solve:

Simplifying
-4 + -1y = 0

Solving
-4 + -1y = 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 + -1y = 0 + 4

Combine like terms: -4 + 4 = 0
0 + -1y = 0 + 4
-1y = 0 + 4

Combine like terms: 0 + 4 = 4
-1y = 4

Divide each side by '-1'.
y = -4

Simplifying
y = -4
Subproblem 2
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
Solution
y = {-4, 5}