Answer:
Part A: -5/9, 6/10, -7/11, 8/12
Part B:

Part C: Positive
Step-by-step explanation:
The given sequence is:

As seen above the sequence is an alternating sequence because it changes in sign
Also, neglecting the sign chnages, we will observe, a common diffference of 1 in the numerator and denominator
a) Therefore, if the pattern continues, the next 4 terms in the sequence are:
-5/9, 6/10, -7/11, 8/12
b)
Without the sign, the explicit equation representing the numerator is calculated below:
1, 2, 3, 4......
The first term, a = 1
The common difference, d = 1
This is an arithmetic sequence
N(n) = a + (n - 1)d
N(n) = 1 + (n - 1)(1)
N(n) = 1 + n - 1
N(n) = n
The explicit equation representing the denominator is calculated below
5, 6, 7, 8........
The first term, a = 5
The common difference, d = 1
D(n) = a + (n - 1)d
D(n) = 5 + (n - 1)(1)
D(n) = 5 + n - 1
D(n) = n + 4
The alternating sequence will include the term below:

Therefore, the explicit equation for f(n) representing the sequence is:

Part C) The sign of f(56) will be:
(-1)^56 = 1
Since this gives us a positive value, the sign of f(56) is positive