Question

if an ap consists of n terms with first term a and Nth term l show that the sum of the Mth term from the beginning and N th term from the end is (a+l).

this question is from rd sharma from page no 9.26 of 50 question.

Answer 1

Given :
First term of A.P is a
nth term =l
Let d be the common difference
nth term=a+(n-1)d
l=a+(n-1)d
d=l-a/n-1 ------------1

Mth term from the beginning
 =a+(m-1)d=a+(m-1)(l-a/n-1 ) ----------------2

Mth term from the end we get:
where we consider first term as l and the common difference=-d
=l+(m-1)(-d)
=l+(m-1)x(-(l-a)/n-1)
=I-(m-1)(l-a)/n-1 --------------3

thus sum of mth term from beginning to end is
=a+(m-1)(l-a/n-1 ) +I-(m-1)(l-a)/n-1
 =a+l
Hence proved

Answer 2

Answer:

Step-by-step explanation:

Hope the below image would work.