my answer is

f[tex]_{n+1}[/tex]+f[tex]_{n+2}[/tex]+f[tex]_{n+3}[/tex].....f[tex]_{n}[/tex]

ive got other ways off doing it in the book but they do not use f[tex]_{n+3}[/tex]

these are

f[tex]_{n+2}[/tex]+f[tex]_{f-1}[/tex]-f[tex]_{n}[/tex]

they all should be in lower case but i can not seam to get the post to do it i hope it does not make it hard to help me with the question.

**3. The Attempt at a Solution**

**1. Homework Statement**

**2. Homework Equations**

**3. The Attempt at a Solution**

**1. Homework Statement**

**2. Homework Equations**

**3. The Attempt at a Solution**

**1. Homework Statement**

**2. Homework Equations**

**3. The Attempt at a Solution**

**1. Homework Statement**

**2. Homework Equations**

**3. The Attempt at a Solution**

**1. Homework Statement**

**2. Homework Equations**

**3. The Attempt at a Solution**