Question

✨ For an A.P., the first term is a and the n" term is 1. How would you find the sum of these n term
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Answer 1

Answer:

number of terms in A.P is n.

first term of A.P is a

1

=a

nth term of A.P is a

n

=l

let d be the common difference

mth term of an A.P from begning is given by

a

m

=a+(m−1)d...….eq(1)

for finding the mth term from the end

the first term becomes a

1

=l

and the common difference becomes −d

now mth term from last is given by

a

m

′

=l+(m−1)(−d)….eq(2)

now, we have to find sum of eq(1) and eq(2)

a

m

+a

m

′

=a+(m−1)d+l−(m−1)d

a

m

+a

m

′

=a+l