S₁, S₂, , S₁₀ are the speakers in a conference. If S₁ addresses only after S₂ , then the number of ways the speakers address is

Step-by-step solution

Since, S₁ speak after S₂ , therefore two places can be chosen out of 10 place is ¹⁰ C₂ ways and rest of the 8 speakers can speak in 8 ! ways. Required number of ways = ¹⁰ C₂ 8 ! aligned & = 10 ! 2 ! 8 ! 8 ! & = 10 ! 2 ! . aligned