B blame_canada100 May 2005 82 0 I LIVE IN QUEBEC,CANADA May 21, 2010 #1 State the common difference or ratio and determine a formula for the nth term. 5,10,20,40,... I got the common difference which is X 2. But I dont get the 2nd part.

State the common difference or ratio and determine a formula for the nth term. 5,10,20,40,... I got the common difference which is X 2. But I dont get the 2nd part.

harish21 Feb 2010 1,036 386 Dirty South May 21, 2010 #2 blame_canada100 said: State the common difference or ratio and determine a formula for the nth term. 5,10,20,40,... I got the common difference which is X 2. But I dont get the 2nd part. Click to expand... The nth term of a geometric sequence with initial value a and common ratio r is given by \(\displaystyle {a_n} = r \times a^{n-1}\) So, The nth term for this sequence would be given by: \(\displaystyle {a_n} = 5 \times 2^{n-1}\) Reactions: blame_canada100

blame_canada100 said: State the common difference or ratio and determine a formula for the nth term. 5,10,20,40,... I got the common difference which is X 2. But I dont get the 2nd part. Click to expand... The nth term of a geometric sequence with initial value a and common ratio r is given by \(\displaystyle {a_n} = r \times a^{n-1}\) So, The nth term for this sequence would be given by: \(\displaystyle {a_n} = 5 \times 2^{n-1}\)

masters MHF Helper Jan 2008 2,550 1,187 Big Stone Gap, Virginia May 21, 2010 #3 blame_canada100 said: State the common difference or ratio and determine a formula for the nth term. 5,10,20,40,... I got the common difference which is X 2. But I dont get the 2nd part. Click to expand... Hi blame_canada100, You didn't find a common difference; you found a common ratio. \(\displaystyle a_n=a_1r^{n-1}\) \(\displaystyle a_n=5(2)^{n-1}\) Continue.... Reactions: blame_canada100

blame_canada100 said: State the common difference or ratio and determine a formula for the nth term. 5,10,20,40,... I got the common difference which is X 2. But I dont get the 2nd part. Click to expand... Hi blame_canada100, You didn't find a common difference; you found a common ratio. \(\displaystyle a_n=a_1r^{n-1}\) \(\displaystyle a_n=5(2)^{n-1}\) Continue....