(y-1)(y+9)=

Solution for (y-1)(y+9)= equation:

Simplifying
(y + -1)(y + 9) = 0

Reorder the terms:
(-1 + y)(y + 9) = 0

Reorder the terms:
(-1 + y)(9 + y) = 0

Multiply (-1 + y) * (9 + y)
(-1(9 + y) + y(9 + y)) = 0
((9 * -1 + y * -1) + y(9 + y)) = 0
((-9 + -1y) + y(9 + y)) = 0
(-9 + -1y + (9 * y + y * y)) = 0
(-9 + -1y + (9y + y2)) = 0

Combine like terms: -1y + 9y = 8y
(-9 + 8y + y2) = 0

Solving
-9 + 8y + y2 = 0

Solving for variable 'y'.

Factor a trinomial.
(-9 + -1y)(1 + -1y) = 0

Subproblem 1
Set the factor '(-9 + -1y)' equal to zero and attempt to solve:

Simplifying
-9 + -1y = 0

Solving
-9 + -1y = 0

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

Add '9' to each side of the equation.
-9 + 9 + -1y = 0 + 9

Combine like terms: -9 + 9 = 0
0 + -1y = 0 + 9
-1y = 0 + 9

Combine like terms: 0 + 9 = 9
-1y = 9

Divide each side by '-1'.
y = -9

Simplifying
y = -9
Subproblem 2
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
Solution
y = {-9, 1}