Question

Find the 20th Term from the last term of the AP : 3,8,13....,253

Answer 1

$\bf{\huge{Answer}}$



[We know that formula of Arithmetic Sequence or Progressions]

l-(n-1)d

[Here]

a=First term

n=Number of terms

l=last terms

d=CommOn difference

ACCORDING TO THE QUESTION;

l-(n-1)d

253-(20-1)5

= 253-(19)5

= 253-95

= 158


Hence, Required term is 158.

Thanks

Answer 2

Solution :

We have, l = Last term = 253

and,

               d = Common difference = 8 - 3 = 5

∴ 20th term from the end = l - (20 - 1)d

                                           = l - 19d

                                           = 253 - 19 × 5

                                           = 253 - 95 = 158