 Hello and welcome to this session. In this session we will discuss a question which says that given the recursive formula for a sequence, find the explicit formula for the sequence. Here, this is the recursive formula given to us. It is given that a n is equal to a n minus 1 minus 1.7 and a 1 is equal to 11.9. Now before starting the solution of this question, we should know some results. First is the recursive formula for an arithmetic sequence is given by a n is equal to a n minus 1 plus d, where n is greater than 1. And second result is the explicit formula for an arithmetic sequence is given by a n is equal to a n plus n minus 1 the whole into d, where n is greater than equal to 1. d is common reference and a n is first term of the sequence. Now these results will work out as the key idea for solving out the given question. Now let us start with the solution of the given question. Now in this question we are given recursive formula for a sequence that is a n is equal to a n minus 1 minus 1.7 and a 1 is equal to 11.9. Now using the result which is given by the key idea, we know that recursive formula for an arithmetic sequence is given by a n is equal to a n minus 1 plus d, where n is greater than 1 and where d is the common difference. Now see that the given recursive formula is of this type. Now on comparing the given recursive formula with a n is equal to a n minus 1 plus d, we get d is equal to minus 1.7. So here common difference d is equal to minus 1.7. Now in this recursive formula we are also given the first term of the sequence that is a n which is equal to 11.9. Now we have first term of the sequence that is a n which is equal to 11.9 and we have the common difference d that is equal to minus 1.7. Now using the second result which is given in the key idea, we know the recursive formula for arithmetic sequence is given by a n is equal to a n plus n minus 1 by whole into d, where n is greater than equal to 1, d is common difference, a n is first term of the sequence, so we will substitute a n is equal to 11.9 and d is equal to minus 1.7 in a n is equal to a n plus n minus 1 by whole into d and we get a n is equal to 11.9 plus n minus 1 by whole into minus 1.7. Now this implies a n is equal to 11.9 minus 1.7 n plus 1.7. Further this implies a n is equal to, now we will combine the light terms, so it will be 11.9 plus 1.7 minus 1.7 n. Now this implies a n is equal to, now 11.9 plus 1.7 is 13.6 minus 1.7 n, further this implies a n is equal to minus 1.7 n plus 13.6 thus the required specific formula for the given arithmetic sequence a n is equal to minus 1.7 n plus 13.6 so this is the required answer and this completes our session, hope you all have enjoyed the session.