Answer :
From the information given,
(x - 3)(x - 5) < 0
We would find where it is equal to zero. Thus,
x - 3 = 0 or x - 5 = 0
x = 3 or x = 5
It is equal to zero at x = 3 and x = 5
Between 3 and 5, the function will either be always greater than 0 or always less than 0. Since we don't know yet, we would test. Let us pick a value in-between 3 and 5 and test it.
Assuming we picked 4
At x = 4, we have
(4 - 3)(4 - 5) < 0
1 * - 1 < 0
- 1 < 0