The sum of the first n terms of the sequence {an} is Sn, and an is the median of Sn and 1. The sequence {BN} satisfies B1 = A1, B4 = S3 (1) Finding the general term formula of sequence {an}, {BN} (2) Let CN = 1 / BN * B (n + 1) and the sum of the first n terms of the sequence {CN} be TN. it is proved that 1 / 3 ≤ TN

RELATED INFORMATIONS

1. It is known that the first n terms and Sn of sequence {an} satisfy Sn = 2an-1, and the arithmetic sequence {BN} satisfies B1 = A1, B4 = 7. Find the general term formula of sequence {an}, {BN}
2. Let P = (a + C, b) and q = (B − a, C − a). If P ‖ Q, then the size of angle c is______ ．
3. In △ ABC, ad is an angular bisector, BP ⊥ ad is at point P, and ab = 5, BP = 2, AC = 9. It is proved that: ∠ ABC = 3 ∠ C
4. In △ ABC, ab = AC, ad is the middle line, P is the upper point of AD, CF ∥ AB is made through point C, and the extension BP intersects AC at point E.1, which proves that BP = PC 2, and the square of BP = PE × pf?
5. It is known that in △ ABC, ab = AC, D is the midpoint of BC side, P is any point on ad, PE ⊥ AB is in E, PF ⊥ AC is in F. try to explain: (1) PE = pf; (2) Pb = PC
6. Let p be a point in Δ ABC, and vector AP = (x-2y) vector AB + (Y-1) vector AC, then the value range of X is--- The value range of Y is-----
7. The middle angle B of triangle ABC is 2 times angle c and ah is perpendicular to BC and h, BM = cm, ab = 2hm
8. An isosceles triangle is an axisymmetric figure. Its axis of symmetry is the middle line on the bottom edge of a and the high line on the bottom edge of B An isosceles triangle is an axisymmetric figure, and its axis of symmetry is A the center line on the bottom edge B the height on the bottom edge The line on which the bisector of C vertex is located D the line where the height of the waist is
9. In the triangle ABC on the right, DC = 2bd, CE = 3aE, the area of the shadow is 20 square centimeters, and the area of the triangle ABC is______ Cm
10. As shown in the figure, in △ ABC, ab = AC, ad ⊥ BC, ad = AE, if ∠ bad = α, then ∠ EBC is equal to
11. Let the first term A1 = a not = 1 / 4 and an + 1 = 1 / 2An n be an even number or an + 1 / 4 n be an odd number, denote BN = a (2n-1) - 1 / 4, n = 1,2,3 Let A1 = a not = 1 / 4 and an + 1 = 1 / 2An n be even or an + 1 / 4 n be odd, denote BN = a (2n-1) - 1 / 4, n = 1, 3 Find the value of A2 and A3 Judge whether {BN} is equal ratio sequence and prove it
12. In the arithmetic sequence an, the sum of the first n terms is Sn, BN = 1 / Sn, B4 = 1 / 10, s6-s3 = 15. Find the general term of BN
13. In the arithmetic sequence {an}, S9 = - 36, S13 = - 104, in the arithmetic sequence {BN}, B5 = A5, B7 = A7, then B6 = () A. ±42B. 42C. ±6D. 6
14. Given two arithmetic sequences {an}, {BN}, the sum of the first n terms is Sn, TN respectively, and Sn / TN = 7n + 2 / N + 3, then A7 / B8= The answer is 31 / 6
15. (2010 Susong County three modules) arithmetic {an} series of the former n items and Sn, S9=-18, S13=-52, geometric ratio {bn}, b5=a5, b7=a7, the value of B15 is () A. 64B. -64C. 128D. -128
16. The sum of the first n terms of the sequence {an} and {BN} is denoted as an and BN respectively. It is known that an = - n-3 / 2,4bn-12an = 13N (n ∈ natural number) (base n after a, B, a, b) ① Find the analytic expression of B base n about N and the general term formula of the sequence {B base n}. ② let C base n = (1 / 2) ∧ 2B base n-3a base n, prove that {C base n} is an equal ratio sequence, and find the first n term and C base n of the sequence {C base n} (thank you for the detailed process
17. If SN: TN = (7n + 1): (4N + 27), find the ratio of a11: B11
18. Proving trigonometric function: cos ^ 2 (a) - cos (2a) * cos (4a) = sin ^ 2 (3a) Verification: cos ^ 2 (a) - cos (2a) * cos (4a) = sin ^ 2 (3a)
19. If 3sina + cosa = 0, then 1 / sin ^ 2A + cos ^ 2A = a.10/3 B.5 / 3 C.2 / 3 d. - 2
20. Simplification 2 / (COS ^ 2a-sin ^ 2a)