Các câu hỏi tương tự
Tính
A=1/2×9+1/9×7+1/7×19+...+1/252×509
B=1/10×9+1/18×13+1/26×17+...+1/802×405
C=2/4×7-3/5×9+2/7×10-3/9×13+...+2/301×304-3/401×405
Bài 1;tính
A=1/2*9+1/9*7+1/7*19+....+1/252*509
B=1/10*9+1/18*13+/26*17+....+1/802*405
C=2/4*7-3/5*9+2/7*10-3/9*13+...+2/301*304-3/401*405
Bài 2
Cho S=1/5^2+1/9^2+...+1/409^2
Chứng minh S<1/12
1+2-3-4+5+6-7-8+9+10...+401+402-403-404+405+406
A=1+2-3-4+5+6-7-8+9+10...+401+402-403-404+405+406
1) Thuc hien phep tinh:
a) 4^6 × 9^2 / 6^3 × 8^2
b) 5^6 × 15^4 /5^4 × 3^3
c) 3^9 - 2^3 × 3^7 + 2^10 × 3^2 - 2^13 / 3^10 - 2^2 × 3^7 + 2^10 × 3^3 - 2^12
d) (1/9)^10 : (1/3)^20
e) (1/64)^5 × (1/4)^7
2) Chung minh rang:
a)2014^100+2014^99 chia het cho 2015
b) 4^13+32^5-8^8 chia het cho 5
c) 81^27-27^9-9^13 chia het cho 405
Help me!! Pleass!!
\(\frac{2}{4\cdot7}-\frac{2}{5\cdot9}+\frac{2}{7\cdot10}-\frac{2}{9\cdot13}+\frac{2}{10\cdot13}-\frac{2}{13\cdot17}+...+\frac{2}{301\cdot304}-\frac{2}{401\cdot405}CM:tich,tren,< \frac{1}{15}\)
Tính tổng sau :
A = 1 + 2 + 3 + 4 + ... + 100
B = 2 + 4 + 6 + 8 + ... + 100
C = 4 + 7 + 10 + 13 + ... + 301
D = 5 + 9 + 13 + 17 + ... + 201
S=1+2-3-4+5+6-7-8+9+10-11-12+13+14...-299-100+301+302
A = 1 . 3 + 3 . 5 + 5 . 7 + ... + 49 . 51
B = 2 . 4 + 4 . 6 + 6 . 8 + ... + 98 . 100
C = 1 . 4 + 4 . 7 + 7 . 10 + ... + 301 . 304
D = 1 . 2 . 3 + 2 . 3 . 4 + ... + 98 . 99 . 100