Question

The first term of an arithmetic sequence is 4 and the fifth term is 16. What is the nth term of the sequence?
A.
4n
B.
3n + 1
C.
5n – 1
D.
4n + 1

Answer 1

aruthmetic
an=a1+d(n-1)
a1=4
5th is 16
a5=4+d(5-1)=16
16=4+d(4)
minus 4
12=d(4)
divide 4
3=d

an=4+3(n-1)
an=4+3n-3
an=4-3+3n
an=1+3n

B is ansres

Answer 2

If the 5th term is stated, all you need to do is plug in 5 for the n value, as it represents the 5th term. The only equation that holds true for the 5th terms being 16 is B. 3n+1
1st term = 3(1)+1 = 4
2nd term = 3(2) +1 = 7
3rd term = 3(3) +1 = 10
4th term = 3(4) +1 = 13
5th term = 3(5)+1 = 16

Correct answer is B. 3n+1