Question

In an arithmetic series, if S7=56, and d=5, then how do you find A1?

Answer 1

Sn if denotes the nth term of ap then Sn=A+(n-1)d

Your question was not clear if it was sum of seven terms or was it the 7th term

Answer 2

Soln : Here ,

S7=56 & d=5.

Then,

S7 =56

=>7/2[2a+(7-1)5]=56

=>7[2a+6×5]=56×2

=>2a+30=(56×2)/7

=>2a+30=8×2

=>2a=16-30

=>2a=-14

=>a=-14/2

=>a=-7

Hence ,a1=-7.