The first and last term of AP are a and l respectively. If S is the sum of all the terms of the AP
and the common difference is given by (l^2-a^2)/k-(l+a) , then k = ?
Solution
Let the common difference and number of terms of AP be
Last term of AP =
and
respectively.
of the AP,
… (1)
Sum of
terms of
[
]
(
)[
(
)[
(
)
(
) ]
]
Comparing with
Thus, the value of
, we get
is
.
Answer: the value of
is
.
(Using (1))