Question

PLEASE!!!

You are practicing your skills at building a house of cards. The world record for the tallest free standing house of cards is over 25 feet high! Use the picture of the house of cards shown to answer the questions that follow.
How can you find the number of cards needed for any row number?
Please justify your answer.

Answer 1

We see on the picture that :
When we go down one row, we add one horizontal and two diagonal cards.

In the first row we have 2 cards
In the second 2+3=5 cards
In the third 5+3=8 cards
etc.

General formula : in the n-th row from the top, we have
`\boxed{ 2+(n-1)\cdot3\text{ cards}}`