Tính:
C= 12*(501x-2004) biết 3*(x-4)= 2003/2004
5^24+5^20+5^16+...+5^4+1/5^26+5^24+5^22+...+5^2+1
chứng minh
1/22+1/32+1/42+1/52+...+1/1002 >3/4
M = 1002– 992 + 982 – 972 + … + 22 – 12;
N = (202+ 182 + 162 + … + 42 + 22) – (192 + 172 + 152 + … + 32 + 12);
P = (-1)n.(-1)2n+1.(-1)n+1.
Chứng minh rằng:
A = 1/3 + 1/32 + 1/33 + ..........+ 1/399 < 1/2
B = 3/12x 22 + 5/22 x 32 + 7/32 x 42 +............+ 19/92 x 102 < 1
C = 1/3 + 2/32 + 3/33 + 4/34 +.........+ 100/3100 ≤ 0
M=(100-1).(100-22).(100-32). ... .(100-502)
Tính B = 1.2.3 + 2.3.4 + ... + (n - 1)n(n + 1)
Tính C = 1.4 + 2.5 + 3.6 + ...+ n(n + 3)
Tính D = 12 + 22 + 32 + ... + n2
Tính B = 1.2.3 + 2.3.4 + ... + (n - 1)n(n + 1)
Tính C = 1.4 + 2.5 + 3.6 + ...+ n(n + 3)
Tính D = 12 + 22 + 32 + ... + n2
(1/49-1/32).(1/49-1/42).....(1/49-1/492)
1 * 2 * 3 * 4 * 5 * 6 * 7 * 8 * 9 * 10 * 11 * 12 * 13 * 14 * 15 * 16 * 17 * 18 * 19 * 20 * 21 * 22 * 23 * 24 * 25 * 26 * 27 * 28 * 29 * 30 * 31 * 32 * 33 * 34 * 35 * 36 * 37 * 38 * 39 * 40 * 41 * 42 * 43 * 44 * 45 * 46 * 47 * 48 * 49 * 50 * 51 * 52 * 53 * 54 * 55 * 56 * 57 * 58 * 59 * 60 * 61 * 62 * 63 * 64 * 65 * 66 * 67 * 68 * 69 * 70 * 71 * 72 * 73 * 74 * 75 * 76 * 77 * 78 * 79 * 80 * 81 * 82 * 83 * 84 * 85 * 86 * 87 * 88 * 89 * 90 * 91 * 92 * 93 * 94 * 95 * 96 * 97 * 98 * 99 * 100 bằng bao nhiêu?
biết:12+22+32+...+102=385.Tính tổng S=22+42+62+...+202