A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 one year ago
The first three terms of an arithmetic sequence, a, a+d and a + 2d, are the same as the first three terms, a, ar, ar^2, of a geometric sequence ( a does not equal 0).
Show that this is only possible if r=1 and d=0
I am not sure how they want me to prove this.
anonymous
 one year ago
The first three terms of an arithmetic sequence, a, a+d and a + 2d, are the same as the first three terms, a, ar, ar^2, of a geometric sequence ( a does not equal 0). Show that this is only possible if r=1 and d=0 I am not sure how they want me to prove this.

This Question is Closed

Koikkara
 one year ago
Best ResponseYou've already chosen the best response.0@imqwerty this user might help you. @Zas

imqwerty
 one year ago
Best ResponseYou've already chosen the best response.1the sum of 1st 3 terms of AP1st term of both the series is a so its clear that a=a :D now we come to the second term\[a+d=ar\] \[d=ara=>d=a(r1)\] nd the third terms are also equal so \[a+2d=ar^2\] put d=a(r1) in this eq. \[a+2a(r1)=ar^2\]divide the whole equation by a u get\[1+2(r1)=r^2 =>r^2 2r+1=0 =>(r1)^2=0\]so r =1 put r=1 in d=a(r1) d=a(11) d=0

imqwerty
 one year ago
Best ResponseYou've already chosen the best response.1hey forget that 1st line i forgot to delete that instead of that it must be 1st terms of both series r same so a=a

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ok, thank you very much!
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.