find the number of ways in which candidates A1,A2,A3,A4,....,A10 CAN BE RANKED IF<1>A1 and A2 are next to each other

Dear abhay

A1,A2,A3,A4,....,A10 total 10 candidates

but A1 and A2 always be together

so A3,A4,....,A10 total 8candidates   + (A1A2)

so these candidate can be ranked in   9! ways  

but A1 and A2 can interchange their rank in 2! ways

so total ways  = 9! *2!

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