find the first negative term of the AP 2000,1990,1980,1970.....

Here is the link given below for the answer similar to your query :

https://www.meritnation.com/ask-answer/question/which-term-of-the-sequence-17-161-5-152-5-143-5/arithmetic-progressions/3446548

Hope this would have clear your doubt. Do let us know in case of any further concerns.