Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
등차수열의 첫 번째 항은 2이고, 공차는 3입니다.deungchasuyeol-ui cheot beonjjae hang-eun 2igo, gongcha-neun 3imnida.The first term of the arithmetic progression is 2, and the common difference is 3.