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\(\frac{7}{13}.\frac{7}{15}-\frac{5}{12}.\frac{21}{39}+\frac{49}{91}.\frac{8}{15}\\ =\frac{7}{13}.\frac{7}{15}-\frac{5}{12}.\frac{7}{13}+\frac{7}{13}.\frac{8}{15}\\ =\frac{7}{13}\left(\frac{7}{15}-\frac{5}{12}+\frac{8}{15}\right)\\ =\frac{7}{13}\left(\frac{7}{15}+\frac{8}{15}-\frac{5}{12}\right)\\ =\frac{7}{13}\left(1-\frac{5}{12}\right)\\ =\frac{7}{13}.\frac{712}{ }\)
\(\frac{7}{13}.\frac{7}{12}=\frac{49}{156}\)
= 7/13 x 7/3x5 - 5/3x4 x 3x7/3x13 + 7x7/7x13 x 2x4 /3x5
=1/13 x 1/5 x 1/3 x 2/1
=2/195
dấu / là đấu gạch _ của phân số đó mình không biết viết phân số trên máy tính bạn có thể chỉ mình không
\(\frac{7}{13}.\frac{7}{15}-\frac{5}{12}.\frac{21}{39}+\frac{49}{91}.\frac{8}{15}\\ =\frac{7}{13}.\frac{7}{15}-\frac{5}{12}.\frac{7}{13}+\frac{7}{13}.\frac{8}{15}\\ =\frac{7}{13}\left(\frac{7}{15}+\frac{8}{15}-\frac{5}{12}\right)\\ =\frac{7}{13}\left(1-\frac{5}{12}\right)\\ =\frac{7}{13}.\frac{7}{12}\\ =\frac{49}{156}\)
7/13.7/15-5/12.21/39+49/91+8/15
=7/13.7/15-5/12.7/13+7/13.8/15
=7/13.(7/15-5/12+8/15)
=7/13.7/12
=49/156
7/13x7/15-5/12x21/39+49/91x8/15
=7/13x7/15-5/12x7/13+7/13x8/15
=7/13x(7/15-5/12+8/15)
=7/13x7/12
=49/156
7/13.7/15-5/12.21/39+49/91.8/15 =7/13.7/15-5/12.7/13+7/13.8/15 =7/13(7/15-5/12+8/15) =7/13.7/12 =49/156
a ) \(\frac{7}{13}\).\(\frac{7}{15}\)-\(\frac{5}{12}\).\(\frac{21}{39}\)+\(\frac{49}{91}\).\(\frac{8}{15}\)
= \(\frac{7}{13}\).(\(\frac{7}{15}\)-\(\frac{5}{12}\)+\(\frac{8}{15}\))
=\(\frac{7}{13}\).\(\frac{7}{12}\)
=\(\frac{49}{156}\)
hok tốt
7/13.7/15-5/12.7/13+7/13.8/15
7/13.(7/15-5/12+8/15)
7/13.7/12
49/156
a ) \(\frac{7}{13}\).\(\frac{7}{15}\)-\(\frac{5}{12}\).\(\frac{21}{39}\)+\(\frac{49}{91}\).\(\frac{8}{15}\)
= \(\frac{7}{13}\).(\(\frac{7}{15}\)-\(\frac{5}{12}\)+\(\frac{8}{15}\))
=\(\frac{7}{13}\).\(\frac{7}{12}\)
=\(\frac{49}{156}\)
hok tốt
\(\frac{7}{13}.\frac{7}{15}-\frac{5}{12}.\frac{21}{39}+\frac{49}{91}.\frac{8}{15}\)
\(=\frac{7}{13}.\frac{7}{15}-\frac{5}{12}.\frac{7}{13}+\frac{7}{13}.\frac{8}{15}\)
\(=\frac{7}{13}.\left(\frac{7}{15}-\frac{5}{12}+\frac{8}{15}\right)\)
\(=\frac{7}{13}.\left(1-\frac{5}{12}\right)\)
\(=\frac{7}{13}.\left(\frac{12}{12}-\frac{5}{12}\right)\)
\(=\frac{7}{13}.\frac{7}{12}\)
\(=\frac{49}{156}\)