a) bn=b1*q^(n-1)
b1=11
b4=11*q^3=88 => q^3=8 =>q=2
Sn=(b1(1-q^n))/(1-q)
s5=(11*(1-32)/1-2)=11*31=341
б) b4=b1*q^3 => 1/81=b1*1/27 => b1=1/3
S=b1/(1-q)=1/3 : (1-1/3) =1/2
a) bn=b1*q^(n-1)
b1=11
b4=11*q^3=88 => q^3=8 =>q=2
Sn=(b1(1-q^n))/(1-q)
s5=(11*(1-32)/1-2)=11*31=341
б) b4=b1*q^3 => 1/81=b1*1/27 => b1=1/3
S=b1/(1-q)=1/3 : (1-1/3) =1/2