Final answer:
To find the value of U23, we can use the given sequence formula U1 = 12, Un = U(n-1) + 9 for n > 2. By applying this formula step by step, we find that U23 = 201.
Step-by-step explanation:
To find the value of U23, we can use the given sequence formula Un = U(n-1) + 9 for n > 2. We start with U1 = 12. By using the formula, we can calculate U2 = U1 + 9 = 12 + 9 = 21. Continuing this process, we can find U3, U4, U5, and so on, until we reach U23.
U2 = 21 + 9 = 30
U3 = 30 + 9 = 39
U4 = 39 + 9 = 48
U22 = 183 + 9 = 192
U23 = 192 + 9 = 201
Therefore, the value of U23 is 201, so the correct option is (b) 201.