231k views
2 votes
Just want to double-check on the question and make I did it correctly.

Just want to double-check on the question and make I did it correctly.-example-1

1 Answer

2 votes

This sequence adds three more blocks for each consecutive figure.

The number of blocks from the first to the fourth figures are:

1, 4, 7, 10, ...

So, it is an arithmetic sequence with first term 1 and the difference d between terms equal to 3.

Thus, the nth term is given by the formula:


\begin{gathered} a_n=a_1+(n-1)d \\ \\ a_n=1+(n-1)3 \end{gathered}

Therefore, the 9th term is:


\begin{gathered} a_9=1+(9-1)3 \\ \\ a_9=1+8\cdot3 \\ \\ a_9=1+24 \\ \\ a_9=25 \end{gathered}

Thus, in the 9th figure, there are 25 blocks.

User Micah
by
7.9k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories