Question

21. Given the pattern below, which recursive formula represents the number of triangles in this sequence?

Answer 1

a1 = 3, an = an - 1 + 2

Step-by-step explanation: Notice that Choices (1) and (2) are not recursive formulas, so both can be eliminated.

The first term has 3 triangles and each term after adds 2 more. This is Choice (4).

Answer 2

its 4

Explanation:

a 1 = 3 , a n = a n - 1 + 2

because if you aply this to the shapes that you see at problem 21 you will see that it meaches them