Question

The first and the last terms of an AP are 10 and 361 respectively. If its common difference is 9 then find the number of terms and their total sum?

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Answer 1

Answer:

40 terms

Solution:

Let last term be n

according to formula we can write

→ $a_n=a_1 + (n-1)d$

Now last term is given 361 and d is 9 and first terms is 10 hence putting the values.

→ $361=10+ (n-1)9$

→ $351= (n-1)9$

→ $39= (n-1)$

→ $40= n$

→ Last term is 40th which means total 40 terms are present .

Answer= 40