Question

Find the `11^(t h)`from the last term (towards the first term) of the AP : `10 , 7, 4, dot dot dot , 62.`

Answer 1

10,7,4...,-62 (AP)
`a_1`=10
`a_2`=7
d=`a_2-a_1`
=7-10
=-3
L=-62
`a_n`=a+(n-1)(d)
-62=10+(n-1)(-3)
(n-1)=24
n=25
`a_(15)`=a+(15-1)d
`a_(15)`=10+(14)(-3)
`a_(15)`=-32