Question

In an AP mth term is n. nth term is m.Find the sum of (m+n)th term.​

Answer 1

Answer:

Using the formula for mth term, we get

am=a1+(m−1)d

Hence 

a1+(m−1)d=n...(i)

Similarly 

a1+(n−1)d=m ...(ii)

Subtracting (ii) from (i)

d(m−1−n+1)=n−m

d(m−n)=n−m

d=−1.

a1+(m−1)(−1)=n

a1−m+1=n

a1=m+n−1

Hence (m+n)th term is 

am+n=a1+(m+n−1)d

=(m+n−1)−(m+n−1)

=0.