Progresiones aritméticas | Ej. 5 #julioprofe

I'll explain how to solve the following problem: The sum of the first 21 terms of an arithmetic progression is 420. The nineteenth term is four times the third term. Find the first term and the common difference. ▪️ Topic: #arithmetic and geometric progressions →    • Progresiones aritméticas y geométricas   ▪️ All #algebra videos →    • 2. Álgebra   ▪️ Go to    / @julioprofe   to become a member of the julioprofe channel and enjoy benefits; At levels 2 and 3, you have access to exclusive videos →    • Members-only videos   ▪️ If you find my videos helpful and would like to support me, you can do so at https://julioprofe.net/donaciones/ ▪️ Follow me on social media → https://linktr.ee/julioprofenet ▪️ Visit my website https://julioprofe.net/ to see all my videos (organized by categories and topics) and the documents I have produced, in the section https://julioprofe.net/documentos/ Good luck in your academic pursuits! #julioprofe