(9+z)(5z+4)=0

Solution for (9+z)(5z+4)=0 equation:

Simplifying
(9 + z)(5z + 4) = 0

Reorder the terms:
(9 + z)(4 + 5z) = 0

Multiply (9 + z) * (4 + 5z)
(9(4 + 5z) + z(4 + 5z)) = 0
((4 * 9 + 5z * 9) + z(4 + 5z)) = 0
((36 + 45z) + z(4 + 5z)) = 0
(36 + 45z + (4 * z + 5z * z)) = 0
(36 + 45z + (4z + 5z2)) = 0

Combine like terms: 45z + 4z = 49z
(36 + 49z + 5z2) = 0

Solving
36 + 49z + 5z2 = 0

Solving for variable 'z'.

Factor a trinomial.
(9 + z)(4 + 5z) = 0

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

Simplifying
9 + z = 0

Solving
9 + z = 0

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

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

Combine like terms: 9 + -9 = 0
0 + z = 0 + -9
z = 0 + -9

Combine like terms: 0 + -9 = -9
z = -9

Simplifying
z = -9
Subproblem 2
Set the factor '(4 + 5z)' equal to zero and attempt to solve:

Simplifying
4 + 5z = 0

Solving
4 + 5z = 0

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

Add '-4' to each side of the equation.
4 + -4 + 5z = 0 + -4

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

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

Divide each side by '5'.
z = -0.8

Simplifying
z = -0.8
Solution
z = {-9, -0.8}