In an, an > 0, A1 = 1, a1 + A2 + a3 = 7, find an and Sn

a1+a2+a3=7
We get a1 + A1 * q + A1 * q ^ 2 = q ^ 2 + Q + 1 = 7
So (Q-2) (Q + 3) = 0
We obtain q = 2 or q = - 3 (an > 0, so we omit)
So an = a1q ^ (n-1) = 2 ^ (n-1)
Sn=a1(1-q^n)/(1-q)=2^n-1

RELATED INFORMATIONS

1. In the equal ratio sequence an, Sn = a1 + A2 + a3=______ fast
2. In the equal ratio sequence {an}, Sn = a1 + A2 +... + an, A3 = S2 + 1, A4 = S3 + 1, then q is the common ratio=
3. In the equal ratio sequence, Sn = a1 + A2 + a3 + +An, given A3 = 2s2 + 1, A4 = 2s3 + 1, what is the common ratio?
4. In the known sequence {an}, a1 + a3 = 10, A4 + A6 = 54, find the sum of the fourth term and the first five terms
5. Given the equal ratio sequence a1 + A6 = 11, A3 * A4 = 32 / 9, find an
6. Given an equal ratio sequence an, a1 + a3 = 10, A4 + A6 = 5 / 4, find A4 and S5
7. Given that {an} is an equal ratio sequence, and a1 + a3 = 10, A4 + A6 = 5 / 4, find A4 and S5
8. If the sequence {an} satisfies that A1, a2-a1, a3-a2,... Are equal ratio sequences with 1 as prime minister and 3 as common ratio, then an______
9. The known sequence {an} satisfies A1, a2-a1, a3-a2 an-an-1,… Is the prime minister is 1, the common ratio is one third of the equal ratio sequence 1 The known sequence {an} satisfies A1, a2-a1, a3-a2 an-an-1,… The prime minister is 1, the common ratio is one-third of the equal ratio series 1. Find the general term formula of sequence {an} 2. If BN = (2n-1) an, find the first n terms and Sn of sequence {BN}
10. The known sequence {an} satisfies A1, A2-A3, a4-a3 , an-a (n-1) is the expression of finding an from the equal ratio sequence (1) with Prime Minister of 1 and common ratio of 1 / 3 (2) If BN = (2n-1) an, find the first n terms and Sn of the sequence {BN} It's wrong. (1) it should be A1, a2-a1, a3-a2 ，
11. The sum of the first n terms of an is Sn, A1 = 2, and the mean difference of A2, A3 is S2 The sum of the first n terms of an is Sn, A1 = 2, and the median of the differences of A2 and A3 is S2, 1. The general formula of an 2. Let BN = log2an, find the first n terms and TN of sequence {BN}
12. Please summarize your problem here, where a1 + A2 + a3 = 18, A2 + a3 + A4 = - 9, and Sn = a1 + 2A2 + 3 (A3 + A4 +) +Then limsn=
13. In the equal ratio sequence an, if a1 + A2 = 3. A3 + A4 = 27. And Q > 0. An and Sn (2) In the arithmetic sequence an, if a3a7 = 12, A2 + A8 = 8, and d > 0, find an and Sn
14. The tangent equation of curve y = ex + 1 at point (0,2) is______ ．
15. The tangent equation and normal equation of the cubic power of y = x at x = - 1, etc
16. Find the point on the square of the curve X = t, y = t, and the third power of Z = t, so that the tangent of the point is parallel to the plane x + 2Y + Z = 4
17. Let the intersection point of cubic-3x of curve C: y = x and straight line x = a (a > 0) be P
18. Let the intersection of the curve C: y = x ^ 3-3x and the straight line x = a (a > 0) be p, and the tangent of the curve C passing through P intersects with the x-axis at the point Q (- A, 0), and the value of a is obtained In a hurry Seeking concrete process
19. 1. The ordinate of the intersection of the tangent of the curve y = x ^ 3 + 11 at point P (1,12) and the Y axis is? 2 1. The ordinate of the intersection of the tangent line of the curve y = x ^ 3 + 11 at point P (1,12) and the Y axis is? 2. Given that the tangent slope of function f (x) = ax ^ 2 + 3x-2 at point (2, f (2)) is 7, then the real number a is?
20. Find the tangent equation of the quadratic curve y equal to x where x equals 1