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\(8\frac{7}{10}+2\frac{3}{4}=\frac{87}{10}+\frac{11}{4}=\frac{174}{20}+\frac{55}{20}=\frac{229}{20}\)
Bạn chỉ cần đưa về phân số xong tính bình thường. Muốn đổi từ hỗn số sang phân số, ta chỉ cần lấy phần nguyên nhân cho mẫu rồi cộng với tử là xong. Chứ bạn cứ hỏi mấy bài dễ như thế này thì k giỏi đc đâu!!!
\(\frac{1}{7}\times3\frac{1}{11}-\frac{1}{7}\times\frac{9}{11}-\frac{1}{7}\)
\(=\frac{1}{7}\times\frac{34}{11}-\frac{1}{7}\times\frac{9}{11}-\frac{1}{7}\)
\(=\frac{1}{7}\left(\frac{34}{11}-\frac{9}{11}-\frac{11}{11}\right)\)
\(=\frac{1}{7}\times\frac{14}{11}\)
\(=\frac{2}{11}\)
a) \(\frac{5}{6}< \frac{6}{7}\)
b) \(\frac{5}{8}=\frac{50}{80}\)
c) \(\frac{3}{4}>\frac{5}{7}\)
d) \(\frac{9}{7}< \frac{8}{5}\)
\(\frac{9}{5}\): \(\frac{7}{6}\)+ \(\frac{3}{2}\): \(\frac{7}{6}\)- \(\frac{8}{5}\)x \(\frac{6}{7}\)
\(\frac{9}{5}\div\frac{7}{6}+\frac{3}{2}\div\frac{7}{6}-\frac{8}{5}\times\frac{6}{7}\)
\(=\frac{9}{5}\times\frac{6}{7}+\frac{3}{2}\times\frac{6}{7}-\frac{8}{5}\times\frac{6}{7}\)
\(=\frac{6}{7}\times\left(\frac{9}{5}+\frac{3}{2}-\frac{8}{5}\right)\)
\(=\frac{6}{7}\times\frac{17}{10}\)
\(=\frac{102}{70}\)
\(=\frac{51}{35}\)
\(\frac{9}{5}:\frac{7}{6}+\frac{3}{2}:\frac{7}{6}-\frac{8}{5}x\frac{6}{7}\)
\(=\frac{9}{5}x\frac{6}{7}+\frac{3}{2}x\frac{6}{7}-\frac{8}{5}x\frac{6}{7}\)
\(=\frac{7}{6}x\left(\frac{9}{5}+\frac{3}{2}-\frac{8}{5}\right)\)
\(=\frac{7}{6}x\frac{17}{10}\)
\(=\frac{119}{60}\)
\(x\)là dấu nhân
a) \(\frac{7}{8}\)=\(\frac{7x1560}{8x1560}\)=\(\frac{10920}{12480}\)
\(\frac{7}{10}\)=\(\frac{7x1248}{10x1248}\)=\(\frac{8736}{12480}\)
\(\frac{7}{13}\)=\(\frac{7x960}{13x960}\)=\(\frac{6720}{12480}\)
\(\frac{7}{12}\)=\(\frac{7x1048}{12x1048}\)=\(\frac{7280}{12480}\)
b) \(\frac{1}{4}\)=\(\frac{1x10}{4x10}\)=\(\frac{10}{40}\)
\(\frac{3}{10}\)=\(\frac{3x4}{10x4}\)=\(\frac{12}{40}\)
\(\frac{9}{40}\)
\(\frac{3}{8}\)=\(\frac{3x5}{8x5}\)=\(\frac{15}{40}\)
hơi dài xíu có gì sai mong bạn thứ lỗi đó là cách quy đồng của mình
\(\frac{7}{1.5}+\frac{7}{5.9}+\frac{7}{9.13}+\frac{7}{13.17}+\frac{7}{17.21}\)
\(=\frac{7}{4}.\left(\frac{4}{1.5}+\frac{4}{5.9}+\frac{4}{9.13}+\frac{4}{13.17}+\frac{4}{17.21}\right)\)
\(=\frac{7}{4}.\left(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+\frac{1}{17}-\frac{1}{21}\right)\)
\(=\frac{7}{4}.\left(1-\frac{1}{21}\right)\)
\(=\frac{7}{4}.\frac{20}{21}=\frac{7.4.5}{4.7.3}\)
\(=\frac{5}{3}\)
~ Rất vui vì giúp đc bn ~
Bài giải
\(\frac{7}{1\cdot5}+\frac{7}{5\cdot9}+\frac{7}{9\cdot13}+\frac{7}{13\cdot17}+\frac{7}{17\cdot21}\)
\(=\frac{7}{4}\left(\frac{4}{1\cdot5}+\frac{4}{5\cdot9}+\frac{4}{9\cdot13}+\frac{4}{13\cdot17}+\frac{4}{17\cdot21}\right)\)
\(=\frac{7}{4}\left(\frac{1}{1}-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+\frac{1}{17}-\frac{1}{21}\right)\)
\(=\frac{7}{4}\left(1-\frac{1}{21}\right)\)
\(=\frac{7}{4}\cdot\frac{20}{21}\)
\(=\frac{35}{21}\)
\(\frac{7}{1\cdot5}+\frac{7}{5\cdot9}+\frac{7}{9\cdot13}+\frac{7}{13\cdot17}+\frac{7}{17\cdot21}\)
\(=\frac{7}{4}\left(\frac{4}{1\cdot5}+\frac{4}{5\cdot9}+\frac{4}{9\cdot13}+\frac{4}{13\cdot17}+\frac{4}{17\cdot21}\right)\)
\(=\frac{7}{4}\left(\frac{1}{1}-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+\frac{1}{17}-\frac{1}{21}\right)\)
\(=\frac{7}{4}\left(1-\frac{1}{21}\right)\)
\(=\frac{7}{4}\cdot\frac{20}{21}\)
\(=\frac{35}{21}\)
\(\frac{7}{1.5}+\frac{7}{5.9}+\frac{7}{9.13}+\frac{7}{13.17}+\frac{7}{17.21}\)
\(=\frac{7}{4}.\left(\frac{4}{1.5}+\frac{4}{5.9}+\frac{4}{9.13}+\frac{4}{13.17}+\frac{4}{17.21}\right)\)
\(=\frac{7}{4}.\left(\frac{1}{1}-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+...+\frac{1}{17}-\frac{1}{21}\right)\)
\(=\frac{7}{4}.\left(1-\frac{1}{21}\right)=\frac{7}{4}.\frac{20}{21}\)
\(=\frac{5}{3}\)
Hg