A =1phan2+1phan6+1phan12+1phan20......+1phan132
Những câu hỏi liên quan
1phan2 + 1phan6 + 1phan12 +1phan20 + 1phan30 +1phan42 +1phan42 +1phan56 +1phan72 =?//???[cach lam luon nhe]
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}\)
=\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}\)
=\(\frac{2-1}{1.2}+\frac{3-2}{2.3}+\frac{4-3}{3.4}+\frac{5-4}{4.5}+\frac{6-5}{5.6}+\frac{7-6}{6.7}+\frac{8-7}{7.8}+\frac{9-8}{8.9}\)
=\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}\)
=\(1-\frac{1}{9}=\frac{8}{9}\)
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1/2 + 1/6 + 1/12 + ... + 1/72
= 1/1.2 + 1/2.3 + 1/3.4 + ... + 1/8.9
= 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ... + 1/8 - 1/9
= 1 - 1/9
= 8/9
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1phan2+1phan -3+1phan4+1phan6
ketqua la bao nhieu? nhanh tick
Ta có: \(\frac{1}{2}+\frac{1}{-3}+\frac{1}{4}+\frac{1}{6}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{6}+\frac{1}{4}\)
\(=\frac{1}{6}+\frac{1}{6}-\frac{1}{4}\)
\(=\frac{1}{3}+\frac{1}{4}=\frac{7}{12}\)
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tính bằng cách thuận tiện :1phan2+1phan6+1phan30+....+1phan90+1phan 110
cho s=1 phan 11+1 phan 12+1phan13+.....+1phan19+1phan20
chung minh rang 1phan2 lon hon S lon hon 1
1phan10×11+1phan11×12+1phan12×13+....1phan49×50
6,25 - x = 3phan 5+1phan6
\(6,25-x=\dfrac{3}{5}+\dfrac{1}{6}\\ 6,25-x=\dfrac{23}{30}\\ x=6,25-\dfrac{23}{30}\\ x=\dfrac{329}{60}\)
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a x 1phan2
\(a\times\frac{1}{2}=\frac{a}{2}\)
Vì số nào nhân với 1 cũng bằng chính số đó thôi
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:hoang chay 60m trong 1phan6.Hoi hoang chay duoc day bao nhieu tronng 54 giay
Cho S = 1/32 + 1/42 + 1/52 + ....... + 1/982 + 1/992 + 1/1002 . Chứng minh S < 1/2
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lam on cho to hoi :
1phan a + 1pan b = 1phan2