2006-09-01 00:56:00 · 9 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
i need to write a recursive fomula...that shows hot to get from one number to the next...so far i kno it starts by adding 7 then adds 4 after that..so how do i write that into a formula...?
2006-09-01 01:01:12 · update #1
well...i dont have to find the next number..i have to write a formula to show how to get from one number to the next...
2006-09-01 01:04:53 · update #2
i need to find a way to relate each number to the previous number...like a(sub n-1) is related to (a sub n) how?
2006-09-01 01:15:51 · update #3
ok, i know it is increasing by 7 +4n...but how do i write that as a formula relating 10 to 3..or 21 to 10...?
2006-09-01 01:19:59 · update #4
Yes it is simply:
1x3 = 3
2x5 = 10
3x7 = 21
4x9 = 36
5x11 =55
6x13 = 78 and so on
the nth term is simply: n(2n+1)
And the difference between two consectutive terms equals:
4n+3 = (n+1)(2(n+1)+1) - n(2n+1)
So for the 1st term n=1 and the 2nd term = 3 +4(1)+3 =10
n=2 for the 2nd term and so the 3rd term = 10+4(2)+3 = 21
n=3 for the 3rd term and so the 4th term = 21+4(3)+3 = 36
And so on....
2006-09-01 01:07:53 · answer #1 · answered by Jimbo 5 · 0⤊ 0⤋
It's a quadratic pattern, which you can find here by looking at the second difference. If you look at the difference between the numbers, 10-3=7, 21-10=11 and 36-21=15 it looks like just a bunch of numbers, but if you look at the difference fo these differences, or the second differece if you will, you'll see that 11-7=4 and that 15-11=4, therefore the rate of change for each value increases by four, so 15+4=19 and 36+19=55 so the next number in the pattern is 55.
2006-09-01 08:03:05 · answer #2 · answered by locomonohijo 4 · 0⤊ 0⤋
3 10 21 36
7 11 15 19
4 4 4
So the next no should be 55.
2006-09-01 14:26:43 · answer #3 · answered by doctorindia 1 · 0⤊ 0⤋
55 the difference between alternate no's are in arithmetic progression with diffence of 4 ( 7, 11,15 so 19 should be next that is 36 + 19 = 55 )
2006-09-01 08:05:20 · answer #4 · answered by Kamps 1 · 0⤊ 0⤋
(10 - 3) = 7
(21 - 10) = 11
(36 - 21) = 15
7 + 4 = 11
11 + 4 = 15
And so on...
2006-09-01 07:58:39 · answer #5 · answered by Sana 2 · 1⤊ 0⤋
I think the answer is there in "locomonohijo"s post.
& ya the next number is 55
2006-09-01 08:15:50 · answer #6 · answered by dkCreAtion 1 · 0⤊ 0⤋
Keep looking. It's there and it's quite obvious.
The next number should be 55 âº
Doug
2006-09-01 08:00:48 · answer #7 · answered by doug_donaghue 7 · 0⤊ 1⤋
n*(2n+1)
2006-09-01 09:06:01 · answer #8 · answered by rwbblb46 4 · 0⤊ 0⤋
i think those number didn't have any patterns.....
2006-09-01 08:02:59 · answer #9 · answered by miszlia 1 · 0⤊ 0⤋