Let 3 consecutive terms in the expansion of (1+x)23 be Tr+1,Tr+2‌ and ‌Tr+3 Coefficient of Tr+1=‌23Cr Coefficient of Tr+2=‌23Cr+1 Coefficient of Tr+3=‌23Cr+2 According to the question, ‌23Cr+1−‌23Cr‌=‌23Cr+2−‌23Cr+1 ⇒ ‌=‌