|April 11th, 2017, 01:15 AM||#1|
Joined: Apr 2016
Working out numbers which are in both sequences.
This question's really stumped me, and I can't seem to find any tutorials on how to answer it...
The nth term of a sequence is 2n + 1
The nth term of a different sequence is 3n 1
Work out the three numbers that are
in both sequences
between 20 and 40
Now the three numbers I managed to get are 25, 31 and 37 (as I assumed it meant the output of both of these sequences needs to be the same as well as being in between 20 and 40). For example 2x18+1= 37 as does 3x12+1= 37.
Yet I still feel I'm going the wrong way around this.
Many thanks in advance
Last edited by skipjack; April 11th, 2017 at 03:05 AM.
|April 11th, 2017, 01:45 AM||#2|
Joined: Sep 2015
$3n+1$ will be odd for $n$ even
the numbers with even index in the 2nd sequence between 20 and 40 are
25,31,37 as you discovered.
Last edited by skipjack; April 11th, 2017 at 03:06 AM.
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