Question

FIND THE. 13 THERM FROM THE LAST TERM OF AN A.P 27,23,19, ,-65

Answer 1

GIVEN AP = 27,23,19,......

REVERSING IT WE GET

-65,-61,-57............

SO NOW

A= -65

D= 4

N = 13 (GIVEN)

→ A13 = A + (13 - 1 )D

A13= A + 12D

A13 = -65 + 12(4)

= -65 + 48

= -17 (ANS)

Answer 2

as we have to find from last so first term will be: -65,

and common difference=27-23(as we can put from any consecutive term)= +4

by applying formula:   nth term= a+(n-1)*d

                                   13th term =-65+{(13-1)*4}

                                                  = -65+(12*4)

                                                  = -65+48

                                                   = -17

so 13 th term from last will be -17