Help urgent maths

considering none of the sums go greater than 8 i'd assume you have to write all the terms out
from your working, though, it seems as though you've got it

well because the sequence starts from 5 you can't just plug it into your formula - you need to do the (sum from 1 to 8) - (sum from 1 to 4) to get the overall sum

as for terms, it's the same as before, just plug in the numbers. i don't think they'd give it from n = 1 to 50 because that's going into further maths territory and they would have given you examples to practice on if that were the case, but identifying that it's a geometric series, as you did, is the key idea i would say.

R u sure my teacher said you can do the sequence from 5 to 8 by making the r value 4 because there’s 4 terms

okay well, just go with what your teacher says, they have a degree and i dont want to confuse you.
hope i was able to help

I got the wrong answer but idk why the black is the ms answer

But if it was a longer sequence what would I do… like if it was up to 50.