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\(a.\) \(\frac{4}{15}.\frac{7}{9}+\frac{4}{15}.\frac{2}{9}\)
\(=\frac{4}{15}\left(\frac{7}{9}+\frac{2}{9}\right)\)
\(=\frac{4}{15}.\frac{9}{9}\)
\(=\frac{4}{15}.1\)
\(=\frac{4}{15}\)
\(b.\) \(\frac{13}{19}.\frac{23}{11}-\frac{13}{19}.\frac{8}{11}-\frac{13}{19}.\frac{4}{11}\)
\(=\frac{13}{19}\left(\frac{23}{11}-\frac{8}{11}-\frac{4}{11}\right)\)
\(=\frac{13}{19}.\frac{11}{11}\)
\(=\frac{13}{19}.1\)
\(=\frac{13}{19}\)
a)4/15 x(7/9+2/9)=4/15x1=4/15
b)13/19x(23/11-8/11-4/11)13/19x1=13/19
Bài 1:Tìm tiếp hai số hạng của dãy số:
1) 1; 6; 11; 16; 21; 26;..31;...36….
2) 1; 5; 9; 13; 17; 21; 25,…29;...33..
3) 2; 5; 12; 15; 22; 25; 32; 35;..42..;..45….
6) 1; 3; 7; 9; 13;15; 19; 21;…25..;..27.
a) \(\frac{16}{35}+\frac{8}{35}=\frac{24}{35}\)
b)\(\frac{160}{77}-\frac{28}{77}=\frac{132}{77}=\frac{12}{1}=12\)
c)\(\frac{72}{180}=\frac{18}{45}\)
d) \(\frac{90}{360}=\frac{1}{4}\)
\(a,\frac{2001}{2002}.\frac{5}{7}.\frac{2002}{5}.\frac{7}{2001}=\left(\frac{2001}{2002}.\frac{7}{2001}\right).\left(\frac{5}{7}.\frac{2002}{5}\right)\)
\(=\frac{7}{2002}.\frac{2002}{7}=1\)
\(b,\frac{5}{7}.\frac{7}{9}.\frac{9}{11}.\frac{11}{13}=\left(\frac{5}{7}.\frac{7}{9}\right).\left(\frac{9}{11}.\frac{11}{13}\right)=\frac{5}{9}.\frac{9}{13}\)
\(=\frac{5}{13}\)
\(\frac{4}{9}\)X \(\frac{7}{5}:\frac{7}{9}\)= \(\frac{28}{45}:\frac{7}{9}=\frac{28}{45}\)X \(\frac{9}{7}=\frac{4}{5}\)
Mk nhanh nhất k mk nha
\(=\frac{4\cdot7}{9\cdot5}\cdot\frac{9}{7}\)
\(=\frac{28\cdot9}{45\cdot7}\)
\(=\frac{252}{315}=\frac{4}{5}\)