Question

b1=0,02 bn=312,5 n=7 найти q=? и Sn=?

Answer 1

bn=b1*q^(n-1)
q^(n-1)=bn/b1
q^(n-1)=312,5/0,02=15625
q^(n-1)=5^6
n-1=6
n=7
S7=b1*(q^7-1)/(q-1)
S7=0,02(78125-1)/(7-1)=0,02*78124/6=1562,48/6=260 31/75