Question

find the 12th term from the end of the following AP 3,5,7,9.....201

Answer 1

here, a=201 and d=5-3=2.
according to the question,
d=(-2)[becoz ap stats from last]
now 12th term = a +11d =201+11* -2
                                       =201+(-22)
                                       =179

Answer 2

as ap is from last
a =201
then d =a2-a1
d=7-9
=-2
so on putting the 12th term=
201+11x-2
201+{-22}
201-22
=179