Answer:
The rule of the arithmetic sequence is 13 - 2n
The 30th term is -47
Step-by-step explanation:
∵ f(n) = 11 and g(n) = -2(n - 1) = -2n + 2
∴ f(n) + g(n) = 11 + -2n + 2 = 13 - 2n
Use n = 1 , 2 , 3 , 4 to check the type of the sequence
∵ n = 1 ⇒ 13 - 2(1) = 11
∵ n = 2 ⇒ 13 - 2(2) = 13 - 4 = 9
∵ n = 3 ⇒ 13 - 2(3) = 13 - 6 = 7
∵ n = 4 ⇒ 13 - 2(4) = 13 - 8 = 5
∵ 11 , 9 , 7 , 5 is an arithmetic sequence with difference -2
∴ The rule of the arithmetic sequence is 13 - 2n
∴ The 30th term = 13 - 2(30) = -47
