# What is my mistake here? I was trying to find F/G factor here

I was trying to derive an expression for F/G factor here for homework. I have attached my working in this picture. I always end up with a (1+i) in the numerator which is not in the actual formula. What am I doing wrong here? I have been working on this all day long and have not been able to figure it out.

• Write out all terms in the case $n=2$ or $n=3$. Oct 16, 2022 at 14:50
• i did it for n=3. Oct 16, 2022 at 15:04
• Should be right. Probably a mistake in that "actual formula" then. Oct 16, 2022 at 15:09
• It could be a difference in assumptions. For example, if you have an account earning an interest rate $i$ compounded annually, and you make a deposit of amount $G$ every year, you'll end up with a greater balance (greater by a factor of $1+i$) if you make those deposits at the beginning of each year than if you make them at the end of each year. Oct 16, 2022 at 15:20
• ah i see that could be the case. Oct 16, 2022 at 15:29