Luis uses cubes to represent each term of a pattern based on a recursive function. The recursive function defined is f(n + 1) = f(n) + 4, where n is an integer and n ≥ 2. The number of cubes used in each of the first two figures is shown below. How many cubes does Luis use in the third, fourth, and fifth figures of the pattern? Fill in the blanks.

Figure 1: 9 cubes

Figure 2: 13 cubes

Figure 3: _____ cubes

Figure 4: ______ cubes

Figure 5: ______ cubes

1 answer

To find the number of cubes used in each figure, we can see that the pattern is increasing by 4 cubes each time.

Figure 3: 13 + 4 = 17 cubes
Figure 4: 17 + 4 = 21 cubes
Figure 5: 21 + 4 = 25 cubes

Therefore, the number of cubes Luis uses in the third, fourth, and fifth figures of the pattern are as follows:

Figure 3: 17 cubes
Figure 4: 21 cubes
Figure 5: 25 cubes