Các câu hỏi tương tự
Qfrac{1}{2x9}+frac{1}{9x7}+frac{1}{7x19}+.......+frac{1}{252x509}Rfrac{1}{10x9}+frac{1}{18x13}+frac{1}{26x17}+.....+frac{1}{802x405}Sfrac{2}{4x7}-frac{3}{5x9}+frac{2}{7x10}-frac{3}{9x13}+.........+frac{2}{301x304}+frac{3}{401x403}
Đọc tiếp
Q=\(\frac{1}{2x9}\)+\(\frac{1}{9x7}\)+\(\frac{1}{7x19}\)+.......+\(\frac{1}{252x509}\)
R=\(\frac{1}{10x9}\)+\(\frac{1}{18x13}\)+\(\frac{1}{26x17}\)+.....+\(\frac{1}{802x405}\)
S=\(\frac{2}{4x7}\)\(-\)\(\frac{3}{5x9}\)+\(\frac{2}{7x10}\)\(-\)\(\frac{3}{9x13}\)+.........+\(\frac{2}{301x304}\)+\(\frac{3}{401x403}\)
Tính tổng bằng cách hợp lí:
a, A= 4/1x5 + 4/5x9 + 4/9x13 + ... + 4/33x37
b. B= 6/4x7 + 6/7x10 + 6/10x13 + ...+ 6/73x76
c, C= 5/1x2 + 5/2x3 + 5/3x4 + ... + 5/99x100
tinh ho to
A=2/1x2+2/2x3+2/3x4+......+2/99x101
B=(1+1/2)x(1+1/3)x(1+1/4)x.......x(1+1/2016)
C=3/1x4+3/4x7+3/7x10+............+3/64x67
D=(1-1/2)x(1-1/3)x(1-1/4)x............x(1-1/20)
1/10x9+1/18x13+1/26x17+...+1/802x405
A = 3/1x4 + 3/4x7 + 3/7x10 +...+ 3/n(n + 3) < 12/5 < B = 1/2^2 + 1/3^2 + 1/4^2 +...+ 1/9^2 < 8/9C = 1/4^2 + 1/6^2 + 1/8^2 +...+ 1/(2n)^2 < 1/4
Xem chi tiết
6)chứng tỏ
a)1/1x2+1/2x3+...+1/9x10 <1
b)1/1x2+1/2x3+...+1/99x100 <1
a)4/1x5+1/5x9+1/9x13+1/13x17+1/17x21<1
Lưu ý:"x" là phép nhân
tính
1/3+1/6 + 1/10+...+1/120
2/3x5+2/5x7+...+2/2013x2015
1/4+1/4x7+1/7x10+...+ 1 /2014x2017
A=3^2/1x4+3^2/4x7+3^2/7x10+...+3^2/97x100
a/ 1/2x9 + 1/9x7+1/7x19+...........+1/252x509
b/1/10x9+1/18x13+1/26x17+..................+1/802x405
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