Answer:
(i) 4n - (2n + 1) = 5n + 1 - (4n)
Since it is arithmetic sequence :
The differences between each term are equal
Term 2 - Term 1 = Term 3 - Term 2
4n - 2n - 1 = 5n + 1 - 4n ( solve for n)
2n - 1 = n + 1
2n - n = 1 + 1
n = 2
(ii) sub n in any term
1st term = 2n + 1 = 2(2) + 1 = 5
2nd term = 4n = 4(2) = 8
3rd term = 5n + 1 = 5(2) + 1 = 11
The difference is 3 between each term
4th term = 3rd term + 3 = 11 + 3 = 14
5th term = 4th term + 3 = 14 + 3 = 17
pattern : 5, 8, 11, 14, 17
(iii) sum = 5 + 8 + 11 + 14 + 17 + 20 + 23 + 26
= 124
Or you can use the sum equation, it's left up to you.
