Question

Find i)${24}^{th}$ term of the A.P.5,8,11,14...
ii)${15}^{th}$ term of the A.P.21,16,11,6,..

Answer 1

Formula,

$a_n=a+(n-1)d$

i)

$a=5,d=8-5=3,n=24$

$a_{24}=5+(24-1)3=74$

ii)

$a=21,d=16-21=-5,n=15$

$a_{15}=21+(15-1)(-5)=-49$