It is known that the proportional series An, An 1296, q 6 Sn 1554 find n and A1. With the process, s

an=a1*6^(n-1)=1296 (1)

sn=a1*(1-6 n) (1-6)=1554, i.e. a1*(6 n-1)=7770 (2).

1)*6 (2) gives 6 n (6 n-1)=7776 7770, and the solution gives 6 n=1296, so, n=4, substituting (1) gives a1=6.

The formula is summed by the proportional sequence, sn = a1 * q n - 1) (q-1) = (an * q - a1) (q-1).

i.e. 1554 = (1296 * 6 - a1) 5 gives a1 = 6

Again, the general formula is an = a1 * q (n-1), i.e. 1296 = 6 n

We get n=4so, n=4, a1=6

The proportional number series is a common term for the male envy cherry blossom pose, the first n term and the male brother ode to the cong cherry pose.

an=a1*6^(n-1)=1296 (1)

sn=a1*(1-6 n) (1-6)=1554, i.e. a1*(6 n-1)=7770 (2).

1)*6 (2) gives 6 n (6 n-1)=7776 7770, and the solution gives 6 n=1296, so, n=4, substituting (1) gives a1=6.

a2an-1=128=a1an

a1+an=66

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a1=64,an=2,sn=(a1-anq)(1-q)=(64-2q) file(1-q)=126

q=1 2,an a1=1 32=q (n-1)n=6 or.

a1=2,an=64,sn=(a1-anq)(1-q)=(2-64q)/(1-q)=126q=2,an/a1=32=q^(n-1)

n=6,8,

an=a1*q^(n-1)=q^(n-1)=64sn=a1*[1-q^n]/(1-q)

1-64q] Cavity socks (1-q).

Dewu Q=2, N=7

a2an-1=a1an=128, and a1+an=66, consider a1 and an as the two roots of the equation x 2-66x+128=0, and get the age delay a1=2, an=64 or a1=64, an=2. Next, let's pick up the keys and calculate it yourself.,You should be able to.,The general term of the ratio is just this modulo formula and n terms and formulas.。

a1*an=a2*an-1=128, and a1+an=66, so a1=2,an=64 or a1=64,an=2;When a1=2,an=64, sn=(a1-an*q) (1-q), the solution obtains the dousha q=2, n=6:::when a1=2, an=64, sn=(a1-an*q) respectful person(1-q), the solution q=1 empty draft state 2,n=6: