Question

ln an A.P if a = -15 ,an = 1 and Sn = - 63​

Answer 1

Answer

step by step explaination:

a= -15

an= 1

Sn= -63

formula used:- Sn= n/2×(a+an)

to find value of "n"

=> (-63)=n/2×(-15+1)

=> -63= n/2×(-14)

=> -63= 7n

=> n= -63/7

[n= -9]

to find the value of "d"

formula used:- an= a+(n-1)×d

=> 1 = -15+(-9-1)×d

=> 1+15= 10d

=> 16 = 10d

=> 16/10= d

d = 8/5

d = 1.6

therefore AP = -15, -13.4,-11.8.........,1

hope you got the right answer :- )