Question

the rule for being the nth item in a certain sequence is n(n+1)/2. what is the 4th term in this sequence ? a.) 4b.)10c.)16d.)20

Answer 1

The 4th term of the sequence can be determined as,

$\begin{gathered} a_n=\frac{n(n+1)}{2} \\ a_4=\frac{4(4+1)}{2} \\ a_4=10 \end{gathered}$

Thus, option (b) is correct.