Question

q=3
s5=484
b1?
b5?

b3=0,024
s3=0,504
b1?
q?

Answer 1

1)b1=s(q-1)/(q^5-1)=484*2/242=4
b5=b1q^4=4*81=324
2)b1=s(q-1)/(q^3-1)=s/(q^2+q+1)
b3=b1q^2⇒b1=b3/q^2
s/(q^2+q+1)=b3/q^2
21/(q^2+q+1)=1/q²
21q²=q²+q+1
20q²-q-1=0
D=1+80=81
q1=(1-9)/40=-1/5⇒b1=0,024/0,04=0,6
q2=(1+9)/40=1/4⇒b1=0,024:1/16=0,384