 Hello and welcome to the session. In this session we discuss the following question which says which term of the AP 26, 24, 22, 20 and so on is the first negative term. So we are given an AP and we need to find its first negative term. First let's see what is the nth term of an AP it is given by tn and this is equal to a plus n minus 1 into d where this a is the first term of the given AP then d is the common difference. So this is the key idea that we use in this question. Let's proceed with the solution now. The given AP is 26, 24, 22, 20 and so on. So this is the AP given to us. Let's see what is the first term of this AP that is given by a and this is 26. Now the common difference d is given by subtracting this first term from the next negative term that is 24. So 24 minus 26 so this is equal to minus 2. So minus 2 is our common difference. Now we need to find the first negative term of this AP. So we assume let the nth term of the given AP be the first negative term. Now the nth term is given by tn so since we have assumed that this tn is the first negative term so obviously this tn would be less than 0. Now let's see what is tn. tn is equal to a plus n minus 1 into d. Now we put the values for a and d so we get tn is equal to 26 plus n minus 1 into minus 2. So this would be equal to 26 plus minus 2n plus 2 that is equal to 26 minus 2n plus 2. So therefore we get tn is equal to 28 minus 2n. Now that we have tn is less than 0 so this means 28 minus 2n would be less than 0. This would further mean 28 is less than 2n or you can say 2n is greater than 28 so from here we have n is greater than 28 upon 2 which means that n is greater than 14. Now that we have n is greater than 14 so this means that n is equal to 15. Now we had assumed that the nth term would be the first negative term of the given AP thus we have that the 15th term is the first negative term of the given AP. So this is our final answer that the 15th term is the first negative term of the given AP so with this we complete the session hope you have understood the solution of this question.