Tính tổng :
H = \(\frac{20}{130}+\frac{20}{195}+\frac{20}{255}+...+\frac{20}{575}\)
Trả lời đầy đủ nhé !!!!!!
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28 tháng 6 2020
Bài làm
\(D=\frac{6}{3,5}+\frac{6}{5.7}+...+\frac{6}{21.23}\)
\(D=3.\left(\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{21.23}\right)\)
\(D=3.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{21}-\frac{1}{23}\right)\)
\(D=3.\left(\frac{1}{3}-\frac{1}{23}\right)\)
\(D=3.\frac{20}{69}\)
\(D=\frac{20}{23}\)
Học tốt
28 tháng 6 2020
Bài làm
\(D=\frac{6}{3.5}+\frac{6}{5.7}+...+\frac{6}{21.23}\)
\(D=3.\left(\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{21.23}\right)\)
\(D=3.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{21}-\frac{1}{23}\right)\)
\(D=3.\left(\frac{1}{3}-\frac{1}{23}\right)\)
\(D=3.\frac{20}{69}\)
\(D=\frac{20}{23}\)
\(E=\frac{20}{11.13}+\frac{20}{13.15}+\frac{20}{15.17}+...+\frac{20}{53.55}\)
\(E=10.\left(\frac{2}{11.13}+\frac{2}{13.15}+\frac{2}{15.17}+...+\frac{2}{53.55}\right)\)
\(E=10.\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+\frac{1}{15}-\frac{1}{17}+...+\frac{1}{53}-\frac{1}{55}\right)\)
\(E=10.\left(\frac{1}{11}-\frac{1}{55}\right)\)
\(E=10.\frac{4}{55}\)
\(E=\frac{8}{11}\)
\(G=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+...+\frac{1}{9900}\)
\(G=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+...+\frac{1}{99.100}\)
\(G=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{99}-\frac{1}{100}\)
\(G=\frac{1}{1}-\frac{1}{100}\)
\(G=\frac{99}{100}\)
Nhớ k cho m nha
TT
6
2 tháng 4 2017
\(\frac{12}{16}=\frac{3}{4}\)
\(\frac{20}{24}=\frac{5}{6}\)
\(\frac{16}{20}=\frac{4}{5}\)
Ta có: 1/4>1/5>1/6
=> \(1-\frac{1}{4}< 1-\frac{1}{5}< 1-\frac{1}{6}\)
\(\Rightarrow\frac{3}{4}< \frac{4}{5}< \frac{5}{6}\)
\(\Rightarrow\frac{12}{16}< \frac{16}{20}< \frac{20}{24}\)
20 tháng 4 2016
a) \(x-10\left(\frac{2}{15.17}+\frac{2}{17.19}+...+\frac{2}{73.75}\right)=\frac{7}{15}\)
\(x-10\left(\frac{1}{15}-\frac{1}{17}+\frac{1}{17}-\frac{1}{19}+...+\frac{1}{73}-\frac{1}{75}\right)=\frac{7}{15}\)
\(x-10\left(\frac{1}{15}-\frac{1}{75}\right)=\frac{7}{15}=>x-\frac{8}{15}=\frac{7}{15}=>x=1\)
b) \(x-10\left(\frac{2}{11.13}+\frac{2}{13.15}+...+\frac{2}{53.55}\right)=\frac{3}{11}\)
\(x-10\left(\frac{1}{11}-\frac{1}{55}\right)=\frac{3}{11}=>x-\frac{8}{11}=\frac{3}{11}=>x=1\)
FF
13 tháng 7 2016
A = \(\frac{2}{1.4}+\frac{2}{4.7}+\frac{2}{7.10}+...+\frac{2}{97.100}\)
A= 2. ( \(\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+...+\frac{1}{97.100}\))
A= 2. ( \(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{97}-\frac{1}{100}\))
A= 2. (\(1-\frac{1}{100}\))
A= 2. \(\frac{99}{100}\)
A= \(\frac{99}{50}\)
3 tháng 2 2017
(-1/4+9/33-5/3)-(-5/4+6/11-48/49)
= -1/4+9/33-5/3+5/4-6/11+48/49
= -1/4+9/33+(-5/3)+5/4+(-6/11)+48/49
= 65/1617
HA
5
24 tháng 2 2019
\(x-\frac{1}{3}=\frac{9}{20}\)
\(x=\frac{9}{20}+\frac{1}{3}\)
\(x=\frac{9\times3+1\times20}{60}\)
\(x=\frac{47}{60}\)
tat ca diem trung cua cac so nay la deu chia het cho 5 va co tu =nhau
so so hang la
(20/130-20/575):0,1+1=655/299
tong tat ca cac so la:
(20/130+20/575):2.655/299~0,2066