# Stuck on this question

Watch
Announcements

Page 1 of 1

Go to first unread

Skip to page:

Report

#2

Firstly, if you don't already know, a geometric progression/sequence is a sequence where to get from one term to the next you need to multiply by a number. This is different to an arithmetic sequence where you add to get from one term to the next.

E.g. 2, 4, 8, 16, 32,...

This is a geometric sequence where the ratio between terms (the multiplier) is equal to 2.

This sequence has nth term

In general, a sequence with first term and ratio has nth term .

To show that a sequence is geometric, you just need to show that there is a constant ratio between terms.

So for part a), first write out the sequence and then explain that the ratio is constant. E.g. the first term will be 1000.

Have a go at that and post your ideas if you get stuck.

If you're familiar with compound interest, then you'll find that part b) can be done in a very similar way.

1

reply

(Original post by

This is a new topic for GCSE but I'm finding that it's not being taught well / at all in schools.

Firstly, if you don't already know, a geometric progression/sequence is a sequence where to get from one term to the next you need to multiply by a number. This is different to an arithmetic sequence where you add to get from one term to the next.

E.g. 2, 4, 8, 16, 32,...

This is a geometric sequence where the ratio between terms (the multiplier) is equal to 2.

This sequence has nth term

In general, a sequence with first term and ratio has nth term .

To show that a sequence is geometric, you just need to show that there is a constant ratio between terms.

So for part a), first write out the sequence and then explain that the ratio is constant. E.g. the first term will be 1000.

Have a go at that and post your ideas if you get stuck.

If you're familiar with compound interest, then you'll find that part b) can be done in a very similar way.

**notnek**)This is a new topic for GCSE but I'm finding that it's not being taught well / at all in schools.

Firstly, if you don't already know, a geometric progression/sequence is a sequence where to get from one term to the next you need to multiply by a number. This is different to an arithmetic sequence where you add to get from one term to the next.

E.g. 2, 4, 8, 16, 32,...

This is a geometric sequence where the ratio between terms (the multiplier) is equal to 2.

This sequence has nth term

In general, a sequence with first term and ratio has nth term .

To show that a sequence is geometric, you just need to show that there is a constant ratio between terms.

So for part a), first write out the sequence and then explain that the ratio is constant. E.g. the first term will be 1000.

Have a go at that and post your ideas if you get stuck.

If you're familiar with compound interest, then you'll find that part b) can be done in a very similar way.

0

reply

Report

#4

(Original post by

See I did write them out and found there was no geometric progression so I must have done something wrong (I photoshopped my working out because I wasn't sure if it was right). So I did 1000 x 1.5^0 = 1000 and then I increased the power by 1 for the second day etc. My results were 1000, 1500, 2250, 3375 and 5062.5. Have I made a mistake?

**MainlyMathsHelp**)See I did write them out and found there was no geometric progression so I must have done something wrong (I photoshopped my working out because I wasn't sure if it was right). So I did 1000 x 1.5^0 = 1000 and then I increased the power by 1 for the second day etc. My results were 1000, 1500, 2250, 3375 and 5062.5. Have I made a mistake?

0

reply

X

Page 1 of 1

Go to first unread

Skip to page:

### Quick Reply

Back

to top

to top