Question

Here is a picture of three towers.

Not all the cubes can be seen in the towers.



Edith uses 1 cube to build tower 1.
Edith uses 6 cubes to build tower 2. There are 5 cubes on the bottom layer.

The sequence below shows the number of cubes used for the bottom layer of each tower.

Answer 1

nth term = the previous number times 4(x-1)

Explanation:

As you see the first tower has 1 then it is 5 for the next tower and then it is 13 for the next tower and then 25. Well this means that as you see, the expressions adds 4 to the previous 4 and then adds to the tower. Let me show you how it works.

Tower 1: 1

Tower 2: 1 + 4 = 5

tower 3 : 5 + 8 = 13

tower 4: 13 + 12 = 25

tower 5: 25 +16 = 41