The terms -2, 1+2k, 4+4k... form an arithmetic sequence. If the sum of the first ten terms is a+bk then give the value of a-b. I got up to finding the common difference (2k+3). I don't know what to do after.
Follow Math Help Forum on Facebook and Google+
sum upto 10 terms will be of the form of c+dk acc. to question S10=a+bk can u calculate the value of a and b??
firstly the the three ters given are not in ap because [( 4+4k) - ( 1 + 2k)] is not equal to [ ( 1+2k)-(-2)]
Originally Posted by ibdutt firstly the the three ters given are not in ap because [( 4+4k) - ( 1 + 2k)] is not equal to [ ( 1+2k)-(-2)] What do you mean? $\displaystyle (4+4k)-(1+2k)=3+2k=(1+2k)-(-2)$
I regret this post is wrong the given terms are in AP with common difference 2k+3. But with three variables a,b and k we need to have some more information to resolve the solution.
Last edited by ibdutt; Jun 23rd 2013 at 08:18 PM.
Okay, let me try this again. Your sum will have a k in it. After all, we are given that the sum is of the form a + bk... -Dan
View Tag Cloud