Question

a☆b=ab分之1+（a+1）(b+x)分之1若2☆1=3分之2则2004☆2005=

Answer 1

2☆1=1/2+1/[(2+1)(1+x)]=2/3

1/[(2+1)(1+x)]=1/6

∴ x=1

2004☆2005

=1/(2004×2005)+1/[(2004+1)(2005+1)]

=1/2004-1/2005+1/2005-1/2006

=1/2004-1/2006

=1/2010012