Math Problem Statement

f(1)=2, f(n)=f(n−1)+1

Solution

You are given the function ff, defined recursively as:

  • f(1)=2f(1) = 2
  • f(n)=f(n1)+1f(n) = f(n - 1) + 1, for n>1n > 1

This recursive definition implies that each subsequent value of f(n)f(n) is the previous value incremented by 1. We can deduce the values of f(n)f(n) for some small nn:

  • f(1)=2f(1) = 2
  • f(2)=f(1)+1=2+1=3f(2) = f(1) + 1 = 2 + 1 = 3
  • f(3)=f(2)+1=3+1=4f(3) = f(2) + 1 = 3 + 1 = 4
  • f(4)=f(3)+1=4+1=5f(4) = f(3) + 1 = 4 + 1 = 5
  • f(5)=f(4)+1=5+1=6f(5) = f(4) + 1 = 5 + 1 = 6
  • And so on...

General form:

This suggests that the function is increasing linearly. In fact, the recursive rule defines an arithmetic sequence. We can generalize it as:

f(n)=f(1)+(n1)f(n) = f(1) + (n - 1)

Since f(1)=2f(1) = 2, we have:

f(n)=2+(n1)=n+1f(n) = 2 + (n - 1) = n + 1

Thus, the general formula for f(n)f(n) is:

f(n)=n+1f(n) = n + 1

Would you like more details or further explanation?

Here are 5 related questions:

  1. What is the value of f(10)f(10)?
  2. How would the function change if f(1)f(1) was a different value?
  3. Can you derive the closed form of another recursive function?
  4. What is the sum of f(n)f(n) from n=1n = 1 to n=5n = 5?
  5. How would the graph of f(n)=n+1f(n) = n + 1 look?

Tip: Recursive definitions are often simplified by recognizing patterns or converting them into a closed formula!

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Math Problem Analysis

Mathematical Concepts

Recursion
Arithmetic Sequences

Formulas

f(n) = f(1) + (n - 1)
f(n) = n + 1

Theorems

Recursive Function Theorem
Arithmetic Sequence Formula

Suitable Grade Level

Grades 6-8