A question was poised to me by one of my students but up till now i cant bfeak the ice on this question.. Lets see if i could be help my math gurus here
Two A.ps have d same first and last term.the first A.p has 21 term with a common differrence of 9.how many terms,has d other A.p if it common difference is 4
1. Sum of first n terms of an A.P.
is
S n = (n/2)[2a +(n -1)d]
2. If Sn Is sum of n terms of an
A.P. whose first term is a and
last term is l,
then S n = (n/2)(a + l)
3. If common difference is d,
number of terms n and the
last term l,
then S n = (n/2)[2l-(n -1)d]
