3/5x7/9-3/5x2/9
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\(\left(\dfrac{6}{11}+\dfrac{5}{11}\right)\times\dfrac{3}{7}=\dfrac{11}{11}\times\dfrac{3}{7}=1\times\dfrac{3}{7}=\dfrac{3}{7}\)
\(\dfrac{3}{5}\left(\dfrac{7}{9}-\dfrac{2}{9}\right)=\dfrac{3}{5}\times\dfrac{5}{9}=\dfrac{1}{3}\)
a) cách1 a) 3/5x7/9-3/5x2/9
=7/15-2/15
=1/3
cách 2 3/5x7/9-3/5x2/9
=3/5x(7/9-2/9)
=3/5x5/9
=1/3
a/ C1:
\(\frac{3}{5}\times\frac{7}{9}-\frac{3}{5}\times\frac{2}{9}=\frac{3}{5}\times\left(\frac{7}{9}-\frac{2}{9}\right)=\frac{3}{5}\times\frac{5}{9}=\frac{1}{3}\)
C2:
\(\frac{3}{5}\times\frac{7}{9}-\frac{3}{5}\times\frac{2}{9}=\frac{7}{15}-\frac{2}{15}=\frac{1}{3}\)
b/ C1:\(\left(\frac{6}{7}-\frac{4}{7}\right):\frac{2}{5}=\frac{2}{7}:\frac{2}{5}=\frac{5}{7}\)
C2: \(\frac{6}{7}:\frac{2}{5}-\frac{4}{7}:\frac{2}{5}=\frac{15}{7}-\frac{10}{7}=\frac{5}{7}\)
c/ C1: \(\frac{8}{15}:\frac{2}{11}+\frac{7}{15}:\frac{2}{11}=\frac{44}{15}+\frac{77}{30}=\frac{11}{2}\)
C2: \(\left(\frac{8}{15}+\frac{7}{15}\right):\frac{2}{11}=1:\frac{2}{11}=\frac{11}{2}\)
1+1+1-3+0-9+8-6+5x7-5+6-9-7-5+4+7
=1+1+1-3+0-9+8-6+35-5+6-9-7-5+4+7
=19
b ) Đặt \(A=\frac{5}{1.3}+\frac{5}{3.5}+\frac{5}{5.7}+...+\frac{5}{101.103}\)
\(\Rightarrow A=\frac{5}{2}\left(\frac{5}{1}-\frac{5}{3}+\frac{5}{3}-\frac{5}{5}+....+\frac{5}{101}-\frac{5}{103}\right)\)
\(\Rightarrow A=\frac{5}{2}\left(5-\frac{5}{103}\right)\)
a)\(\frac{3}{7}\times\frac{1}{3}+\frac{10}{7}=\frac{1}{7}+\frac{10}{7}=\frac{11}{7}\)
b)\(\frac{9}{5}-\left(\frac{27}{36}-\frac{4}{36}\right)=\frac{9}{5}-\frac{23}{36}=\frac{324}{180}-\frac{115}{180}=\frac{209}{180}\)
a)3/7: 3+5x2/7
=1/7+10/7
=11/7
b)9/5-(3/4-1/9)
=9/5-23/36
=209/180
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