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\(A=1\frac{1}{2}\cdot1\frac{1}{3}\cdot1\frac{1}{4}\cdot...\cdot1\frac{1}{2015}\)
\(\Rightarrow A=\frac{3}{2}\cdot\frac{4}{3}\cdot\frac{5}{4}\cdot...\cdot\frac{2016}{2015}\)
\(\Rightarrow A=\frac{3\cdot4\cdot5\cdot...\cdot2016}{2\cdot3\cdot4\cdot...\cdot2015}=\frac{2016}{2}=1008\)
Vậy A = 1008
1, =\(\frac{2\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{9}-\frac{1}{11}\right)}{4\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{9}-\frac{1}{11}\right)}=\frac{1}{2}\)
2, A=\(\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot...\cdot\frac{99}{100}\)
= \(\frac{1\cdot2\cdot3\cdot....\cdot99}{2\cdot3\cdot4\cdot...\cdot100}=\frac{1}{100}\)
Vậy ......
hok tốt
\(A=1\frac{1}{2}.1\frac{1}{3}....1\frac{1}{2015}\)
\(=\frac{3}{2}.\frac{4}{3}......\frac{2016}{2015}\)
\(=\frac{2016}{2}=1008\)
A=\(1\frac{1}{2}.1\frac{1}{3}.1\frac{1}{4}....1\frac{1}{2015}\)
A=\(\frac{3}{2}.\frac{4}{3}.\frac{5}{4}....\frac{2016}{2015}\)
A=\(\frac{3.4.5.....2016}{2.3.4....2015}\)
A=\(\frac{2016}{2}=1008\)
nhanh tay lên các bạn ai trả lời đầu tiên mình cho 5 cái tick
A=3/4x8/9x15/16x24/25x...x899/900
A=1.3/22 x 2.4/33 x 3.5/42 x 4.6/55 x ... x 29.31/302
A=1.2.3.4...29/2.3.4.5...30 x 3.4.5.6...31/2.3.4.5...30
A=1/30 x 31/2
A=31/60
A =(1/2 +1)×(1/3 +1)×(1/4 +1)×....×(1/99 +1)
=3/2x4/3x...............x100/99
=2-1/99
=197/99
A= \(\frac{3}{2}\cdot\frac{4}{3}\cdot\frac{5}{4}\cdot.....\cdot\frac{100}{99}\)
A=\(\frac{\left(3\cdot4\cdot5\cdot....\cdot99\right)\cdot100}{2\cdot\left(3\cdot4\cdot5\cdot...\cdot99\right)}\)
A=\(\frac{100}{2}=50\)
\(\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+...+\frac{2}{97\cdot99}\)
\(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{99}\)
=> \(\frac{1}{3}-\frac{1}{99}=\frac{32}{99}\)>\(\frac{32}{100}\)=32%
Bài 1a:
A = \(\frac{7^2}{7.8}\times\frac{8^2}{8.9}\times\ldots\times\frac{11^2}{11.12}\)
A = \(\frac{7.8.9.\ldots11}{7.8.\ldots11}\) x \(\frac{7.8.9\ldots11}{8.9.12}\)
A = 7/12
Bài 1B
B = (1+ 1/11).(1 + 1/12)...(1+ 1/15)
B = (11/11 + 1/11).(12/12 + 1/12)...(15/15+ 1/15)
B = 12/11.13/12....16/15
B = 16/11
a, \(A=\frac{22}{27}\)
b,\(B=\frac{1}{57}\)
C,\(C=\frac{1}{50}\)
d, \(D=0\)
Câu a:
A = -1/2 - (-3)/5 + (-1/9) + 1/27 + 7/18 + 4/35 - (-2/7)
A = -1/2 + 3/5 - 1/9 + 1/27 + 7/18 + 4/35 + 2/7
A = (-1/2 - 1/9 + 7/18 + 1/27) + (3/5 + 4/35 + 2/7)
A = (-27/54 - 6/54 + 21/54 + 2/54) + (21/35 + 4/35 + 10/35)
A = -10/54 + 1
A = -5/27 + 1
A = 22/27