q36

[Saumyojit]

The number of permutations of letters a,b,c,d,e,f,g so that neither the pattern beg nor acd appears is

Please tell me the approach or give hint​

 

[pka]

The number of permutations of letters a,b,c,d,e,f,g so that neither the pattern beg nor acd appears is
Please tell me the approach or give hint

How many rearrangements contain the pattern beg. How many contain acd ? How many contain both?
HINT: If [imath]A~\&~B[/imath] are two finite sets then [imath]\|A\cup B\|=\|A\|+\|B\|-\|A\cap B\|[/imath]

 

[Saumyojit]

its done