What is the formula of 2,1,0,-1 Answer: an = -n + 3 Step-by-step explanation: The arithmetic sequence general rule or formula: an = a₁ + (n-1)(d) Where: an = last term ⇒ -1 a₁ = first term ⇒ 2 d = common difference ⇒ (1-2 = 0-1) ⇒ -1 n = nth term in the sequence or the number of terms ⇒ unknown Find the formula or general rule for 2,1,0,-1: an = 2 + (n-1)(-1) an = 2 + 1 - n an = 3 - n an = -n + 3