geometric progession help

The only way to solve this was to use logs, as said before, you need to go through your book again.

this isnt a log question its geometric progression

The only way to find n is by logarithms.

ok, do you have the green pure mathematics c1 c2 textbook is that what you used

I used the edexcel modular text books.

These are what I am using, I can recommend them, I'm just finishing up the geometric sequences and series chapter and it's been made clear as day that you use logs for those problems.

im not doing edxcel though im doing ocr mei

If your book isn't easy enough for you to understand you could try the Edexcel ones for the topics that both specifications cover. It can't exactly hurt, besides the specs aren't going to vary too widely if they cover the same specific topic at the same level.

ok thanks man for advice. btw i got a C in c1 is that bad or ok

hey man, solve 3*5^x=150 giving it to 4dp

is it; log3*5^x=log150

5^x=log150/log3

5^x=4.560876795 then i dont know how to get the x on its own

Depends, did you want a C or above a C?

I haven't taken any maths exams yet, I'm doing all 6 units this coming exam period.

Divide by 3 first, so 5^x = 50

Take logs of both sides so log(5^x) = log(50)

Does this look more familiar?

Edit: Oops , didn't realise there was more than 1 page... Ignore me xD