Ivathematics1. In an AP if a = 1, S2 = 64 and an = 15. Then the value

1.	Ivathematics1. In an AP if a = 1, S2 = 64 and an = 15. Then the value of na) 8B) 7D) 46
Answer» option d is the best answer (c) 6 is the correct answer an= 15let difference =da+(n-1)d= 15----(1)sn= 64n/2{2a+(n-1)d}=64n{a+a+(n-1)d}=128n{1+15)=128since a+(n-1)d=1516n=128n= 128/16=8 option (A) is the correct answer option (a) is the correct one Option ( c = 6) is the right answer is the a = 1, s= 64, an = 15,64 = n/2(a+an)64 = n/2(1+15)64 = n/2(16)128= 16nn = 128/16n = 8so, option (a) is correct. (d) option is correct

Ivathematics1. In an AP if a = 1, S2 = 64 and an = 15. Then the value of na) 8B) 7D) 46

Answer»

option d is the best answer

an= 15let difference =da+(n-1)d= 15----(1)sn= 64n/2{2a+(n-1)d}=64n{a+a+(n-1)d}=128n{1+15)=128since a+(n-1)d=1516n=128n= 128/16=8

option (A) is the correct answer

option (a) is the correct one

Option ( c = 6) is the right answer is the

a = 1, s= 64, an = 15,64 = n/2(a+an)64 = n/2(1+15)64 = n/2(16)128= 16nn = 128/16n = 8so, option (a) is correct.

(d) option is correct