(1+y)(4y-5)=0

Solution for (1+y)(4y-5)=0 equation:

Simplifying
(1 + y)(4y + -5) = 0

Reorder the terms:
(1 + y)(-5 + 4y) = 0

Multiply (1 + y) * (-5 + 4y)
(1(-5 + 4y) + y(-5 + 4y)) = 0
((-5 * 1 + 4y * 1) + y(-5 + 4y)) = 0
((-5 + 4y) + y(-5 + 4y)) = 0
(-5 + 4y + (-5 * y + 4y * y)) = 0
(-5 + 4y + (-5y + 4y2)) = 0

Combine like terms: 4y + -5y = -1y
(-5 + -1y + 4y2) = 0

Solving
-5 + -1y + 4y2 = 0

Solving for variable 'y'.

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

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

Simplifying
-1 + -1y = 0

Solving
-1 + -1y = 0

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

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

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

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

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

Simplifying
y = -1
Subproblem 2
Set the factor '(5 + -4y)' equal to zero and attempt to solve:

Simplifying
5 + -4y = 0

Solving
5 + -4y = 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 + -4y = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -4y = 0 + -5
-4y = 0 + -5

Combine like terms: 0 + -5 = -5
-4y = -5

Divide each side by '-4'.
y = 1.25

Simplifying
y = 1.25
Solution
y = {-1, 1.25}