Geometric and arithmetic progression

Watch
bl64
Badges: 8
Rep:
?
#1
Report Thread starter 6 years ago
#1
Find x and y given that x+3y, 4 and 2x+ 2y are consecutive terms of a geometric series

and x+4y, 4 and x-2y are consecutive terms of an arithemtic series

I'm not even sure how to start
0
reply
BabyMaths
  • Study Helper
Badges: 0
Rep:
?
#2
Report 6 years ago
#2
(Original post by bl64)
Find x and y given that x+3y, 4 and 2x+ 2y are consecutive terms of a geometric series

and x+4y, 4 and x-2y are consecutive terms of an arithemtic series

I'm not even sure how to start
For an arithmetic sequence the difference between any term and the previous term is a constant. Can you use that to write an equation?
0
reply
ztibor
Badges: 10
Rep:
?
#3
Report 6 years ago
#3
(Original post by bl64)
Find x and y given that x+3y, 4 and 2x+ 2y are consecutive terms of a geometric series

and x+4y, 4 and x-2y are consecutive terms of an arithemtic series

I'm not even sure how to start
For three consecutive terms in an arithmetic sequence the middle term is
arithmetic mean of the other two terms (the previous one and the following one)

For three consecutive terms in a geometric sequence the middle term is
geometric mean of the other two terms (the previous one and the following one)

arithmetic mean of A and B is:

\displaystyle \frac{A+B}{2}

geometric mean of A and B is:

\displaystyle \sqrt{A\cdot B}
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Current uni students - are you thinking of dropping out of university?

Yes, I'm seriously considering dropping out (48)
16.22%
I'm not sure (8)
2.7%
No, I'm going to stick it out for now (101)
34.12%
I have already dropped out (4)
1.35%
I'm not a current university student (135)
45.61%

Watched Threads

View All