Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
c, 1/3-1/4+1/4-1/5+........+1/50-1/51
= 1/3-1/51
= 16/51
d, (đề bài)
= 1/1.5+1/5.9 +.........+1/97.101
=1/1-1/5+1/5-1/9+.....+1/97-1/101
=1/1-1/101
= 100/101
d, \(\frac{1}{1.5}+\frac{1}{5.9}+...+\frac{1}{97.101}\)
\(=\frac{1}{1}-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+...+\frac{1}{97}-\frac{1}{101}\)
\(=\frac{1}{1}-\frac{1}{101}=\frac{100}{101}\)
a) \(\frac{4}{11}-\frac{7}{15}+\frac{7}{11}-\frac{5}{15}\)
\(=\left(\frac{4}{11}+\frac{7}{11}\right)-\left(\frac{7}{15}+\frac{5}{15}\right)\)
\(=1-\frac{4}{5}\)
\(=\frac{1}{5}\)
b) \(\frac{7}{3}-\frac{4}{9}-\frac{1}{3}-\frac{5}{9}\)
\(=\left(\frac{7}{3}-\frac{1}{3}\right)-\left(\frac{4}{9}+\frac{5}{9}\right)\)
\(=2-1\)
\(=1\)
c) \(\frac{1}{4}+\frac{7}{33}-\frac{5}{3}\)
\(=\frac{-1}{4}+\frac{-16}{11}\)
\(=\frac{-75}{44}\)
d) \(\frac{-3}{4}\times\frac{8}{11}-\frac{3}{11}\times\frac{1}{2}\)
\(=\frac{-6}{11}-\frac{3}{22}\)
\(=\frac{15}{22}\)
e) \(\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+\frac{1}{99}+\frac{1}{143}+\frac{1}{195}\)
\(=\frac{1}{3\times5}+\frac{1}{5\times7}+\frac{1}{7\times9}+\frac{1}{9\times11}+\frac{1}{11\times13}+\frac{1}{13\times15}\)
\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}\)
\(=\frac{1}{3}-\frac{1}{15}\)
\(=\frac{4}{15}\)
a)(5\(\frac{2}{7}\). \(\frac{8}{11}\)+ \(\frac{2}{11}\).5\(\frac{2}{7}\)): 3\(\frac{4}{11}\)- 1\(\frac{3}{7}\)
= 5\(\frac{2}{7}\). (\(\frac{8}{11}\)+\(\frac{2}{11}\)):\(\frac{37}{11}\)-\(\frac{10}{7}\)
= \(\frac{37}{7}\).\(\frac{8}{11}\).\(\frac{11}{37}\)-\(\frac{10}{7}\)
= \(\frac{37.8.11}{7.11.37}\)- \(\frac{10}{7}\)
= \(\frac{8}{7}\)-\(\frac{10}{7}\)
= \(\frac{-2}{7}\)
\(\frac{5}{11}.\frac{3}{7}+\frac{5}{7}.\frac{4}{11}-\frac{3}{11}\)
\(=\frac{3}{11}.\frac{5}{3}.\frac{3}{7}+\frac{5}{7}.\frac{4}{3}.\frac{3}{11}-\frac{3}{11}\)
\(=\frac{3}{11}.\left(\frac{5}{7}+\frac{20}{21}-1\right)\)
\(=\frac{3}{11}.\left(\frac{15+20}{21}-1\right)\)
\(=\frac{3}{11}.\left(\frac{35}{21}-1\right)\)
\(=\frac{3}{11}.\frac{14}{21}\)
\(=\frac{14}{77}\)
5/11 x 3/7 + 5/7 x 4/11 - 3/11
= 5/11 x 3/7 + 5/11 x 4/7 - 3/11
= 5/11 x ( 3/7 + 4/7 ) - 3/11
= 5/11 x 1 - 3/11
= 5/11 - 3/11
= 2/11
Tk nha !!
\(3\frac{14}{19}+\frac{13}{17}+\frac{35}{43}+6\frac{5}{19}+\frac{8}{43}\)
\(=\left(3\frac{14}{19}+6\frac{5}{19}\right)+\left(\frac{35}{43}+\frac{8}{43}\right)+\frac{13}{17}\)
\(=10+1+\frac{13}{17}=11+\frac{13}{17}=11\frac{13}{17}\)
\(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{11}+1\frac{5}{7}\)
\(=\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{11}+1+\frac{-5}{7}.\left(-1\right)\)
\(=\frac{-5}{7}\left(\frac{2}{11}+\frac{9}{11}-1\right)+1\)
\(=\frac{-5}{7}.0+1==0+1=1\)
\(a)15\frac{3}{13}-\left(3\frac{4}{7}+8\frac{3}{13}\right)\)
\(=15\frac{3}{13}-3\frac{4}{7}-8\frac{3}{13}\)
\(=15\frac{3}{13}-8\frac{3}{13}-3\frac{4}{7}\)
\(=7-3\frac{4}{7}\)
\(=6\frac{7}{7}-3\frac{4}{7}=3\frac{3}{7}\)
\(b)\left(7\frac{4}{9}+4\frac{7}{11}\right)-3\frac{4}{9}\)
\(=7\frac{4}{9}-4\frac{7}{11}-3\frac{4}{9}\)
\(=7\frac{4}{9}-3\frac{4}{9}-4\frac{7}{11}\)
\(=4-4\frac{7}{11}=\frac{7}{11}\)
Bài làm
a) \(-\frac{3}{7}+\frac{3}{4}:\frac{3}{14}\)
= \(-\frac{3}{7}+\frac{3}{4}.\frac{14}{3}\)
= \(-\frac{3}{7}+\frac{7}{2}\)
\(=-\frac{7}{14}+\frac{49}{14}\)
\(=\frac{42}{14}=3\)
b) \(5-\frac{7}{39}:\frac{7}{13}+\frac{8}{9}:4\)
\(=5=\frac{7}{39}.\frac{13}{7}+\frac{8}{9}.\frac{1}{4}\)
\(=5-\frac{1}{3}+\frac{2}{9}\)
\(=\frac{45}{9}-\frac{3}{9}+\frac{2}{9}\)
\(=\frac{44}{9}\)
c) \(\left(\frac{5}{12}:\frac{11}{6}+\frac{5}{12}:\frac{11}{5}\right)-\frac{-7}{12}\)
\(=\left(\frac{5}{12}.\frac{6}{11}+\frac{5}{12}.\frac{5}{11}\right)+\frac{7}{12}\)
\(=\left[\frac{5}{12}\left(\frac{6}{11}+\frac{5}{11}\right)\right]+\frac{7}{12}\)
\(=\frac{5}{12}+\frac{7}{12}\)
\(=\frac{12}{12}=1\)
d) \(-\frac{5}{9}+\frac{14}{9}\left(\frac{3}{4}-\frac{2}{5}\right):49\)
\(=-\frac{5}{9}+\frac{14}{9}\left(\frac{15}{20}-\frac{8}{20}\right):49\)
\(=-\frac{5}{9}+\frac{14}{9}.\frac{7}{20}.\frac{1}{49}\)
\(=-\frac{5}{9}+\frac{7}{9}.\frac{7}{10}.\frac{1}{7.7}\)
\(=-\frac{5}{9}+\frac{1}{90}\)
\(=-\frac{50}{90}+\frac{1}{90}=-\frac{49}{90}\)
\(=\frac{4}{7}\left(2+-\frac{6}{11}-\frac{5}{11}\right)=\frac{4}{7}\left(2-1\right)=\frac{4}{7}\)
Đ_V_T cho mình hỏi vs ạ? 2 ở đâu ạ?