find the nth term of this number sequence
7,12,17
MathBot Answer:
$$7,12,17,...$$This infinite sequence is an arithmetic sequence. The nth term rule for the sequence is $a_n=5 n + 2$, where $n>0$. The recursive formula is $a_n=a_{n-1} + 5$, where $n>1$ and $a_{1}=7$.
$$\begin{matrix}7&&12&&17\\[6pt]&+5&&+5\\[6pt]\end{matrix}$$
Explicit Formula
The formula for an arithmetic sequence where $a_1$ is the 1st term, $d$ is the common difference, and $n$ is the term number is $$a_n=a_1 + d (n - 1)$$
Find $a_1$ and $d$: $$\begin{aligned} a_1&=7 \\ d&=5 \end{aligned}$$
The nth term rule is:$$\begin{aligned} a_n&=a_1 + d (n - 1) \\ &=7 + 5 (n - 1) \\ &=5 n + 2 \end{aligned}$$
Recursive Formula
The formula for an arithmetic sequence where $a_{n-1}$ is the (n-1)th term, $d$ is the common difference, and $n>1$ is $$a_n=a_{n-1} + d$$
Find $d$: $$\begin{aligned} d=5 \end{aligned}$$
The nth term rule is:$$\begin{aligned} a_n&=a_{n-1} + d \\ &=a_{n-1} + 5 \\ &=a_{n-1} + 5 \end{aligned}$$
asked 9 days ago
active 9 days ago