Question

how many terms of the AP 78 71 and 64 needed to give the sum of 468 also find the last term of the AP​

Answer 1

Answer:

here, a=78, a1= 71 and a3=64Let the no. of terms be n. Sn= n/2{2a+(n-1) d} And after u solve this u can find the last term by using the formula Sn =last term(n-1)d Sn =n/2{156+(n-1) (-7) put it as equation ( i ) and then Sn= last term(n-1)(-7)try solving it in copy

Answer 2

Answer:

13th term, -6

Step-by-step explanation:

78+71+64+57+50+43+36+29+22+15+8+1-6 = 468

hence the 13 terms needed to give the sum 468

and -6 is the last term of this AP