a2*a(n-1)=a1*q*a(n-1)=a1*a(n)=128
a1+an=66
a1=2,an=64
Sn=a1+a1*q+q1*q^2+...+An
qSn=a1q+a1q^2+an+an*q
(1-q)Sn=a1-an*q=2-64q=(1-q)126
q=2
n=6
a2*a(n-1)=a1*q*a(n-1)=a1*a(n)=128
a1+an=66
a1=2,an=64
Sn=a1+a1*q+q1*q^2+...+An
qSn=a1q+a1q^2+an+an*q
(1-q)Sn=a1-an*q=2-64q=(1-q)126
q=2
n=6