Question

find the fourth term from the end in an A.P-11,-8,-5,...... 49.

Answer 1

on writing the AP in reverse way, 49,46,....,-8,-11
a=49 ,d=-8-(-11)=3 from left to right,d=-3 in reverse direction
fourth term=a+(n-1)d,n=4
=49+3d
=49-3×3
=49-9=40

Answer 2

a=-11 d=3 l=49
an =l-(n-1)d
=49-3*3
= 49-9=40