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\(\dfrac{2}{9}\cdot\dfrac{5}{17}+\dfrac{7}{9}+\dfrac{2}{9}\cdot\dfrac{12}{17}\)
\(=\dfrac{2}{9}\left(\dfrac{5}{17}+\dfrac{12}{17}\right)+\dfrac{7}{9}\)
\(=\dfrac{2}{9}+\dfrac{7}{9}\)
=1
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#)Giải :
\(\frac{2}{9}.\frac{5}{17}+\frac{2}{9}.\frac{13}{17}-\frac{2}{9}.\frac{1}{17}+2018\frac{7}{9}\)
\(=\frac{2}{9}\left(\frac{5}{17}+\frac{13}{17}-\frac{1}{17}\right)+2018\frac{7}{9}\)
\(=\frac{2}{9}.1+2018\frac{7}{9}\)
\(=\frac{2}{9}+2018\frac{7}{9}\)
\(=2018\frac{9}{9}=2019\)
#~Will~be~Pens~#
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Câu 2:
\(\dfrac{7}{9}\cdot\dfrac{3}{35}=\dfrac{1}{5}\cdot\dfrac{1}{3}=\dfrac{1}{15}\)
\(\dfrac{9}{22}\cdot55=\dfrac{9\cdot55}{22}=\dfrac{9\cdot5}{2}=\dfrac{45}{2}\)
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A,17/12+9/7-2/7+7/12=(17/12+7/12)+(9/7-2/7)=24/12+7/7=2+1=3
B,9/8-(17/7-3/7)+7/8=(9/8+7/8)-14/7=16/8-14/7=2-2=0
Nhớ k nha
a, 17/12+9/7-2/7+7/12
=(17/12+7/12)+(9/7-2/7)
=24/12+7/7
=2+1
=3
b, 9/8-(17/7-3/7)+7/8
=9/8-14/7+7/8
=(9/8+7/8)-14/7
=16/8-14/7
=2-2
=0
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Câu 1: Tìm x:
a) 2/5× x =(thiếu đề)
8/7: x =4/5
x=8/7:4/5
x=10/7
Câu 2: Tính bằng cách thuận tiện nhất
5/9× 8/17 + 4/9 × 8/17
=(5/9+4/9)x8/17
=1x8/17=8/17
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\(\dfrac{2}{9}\cdot\dfrac{5}{17}+\dfrac{2}{9}\cdot\dfrac{12}{17}-\dfrac{1}{9}\\ \\ \\ =\dfrac{2}{9}\cdot\left(\dfrac{5}{17}+\dfrac{12}{17}\right)-\dfrac{1}{9}\\ \\ \\ =\dfrac{2}{9}\cdot1-\dfrac{1}{9}\\ \\ \\ =\dfrac{2}{9}-\dfrac{1}{9}=\dfrac{1}{9}\)
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\(\frac{2}{9}\times\frac{5}{17}+\frac{7}{9}+\frac{2}{9}\times\frac{12}{17}\)
\(=\frac{2}{9}\times\left(\frac{5}{17}+\frac{12}{17}\right)+\frac{7}{9}\)
\(=\frac{2}{9}\times1+\frac{7}{9}\)
\(=\frac{2}{9}+\frac{7}{9}\)
\(=1\)
\(\frac{2}{9}\)× \(\frac{5}{17}\)+ \(\frac{7}{9}\)+\(\frac{2}{9}\)×\(\frac{12}{17}\)
= \(\frac{2}{9}\)×( \(\frac{5}{17}\)+\(\frac{12}{17}\)) + \(\frac{7}{9}\)
= \(\frac{2}{9}\)× \(\frac{17}{17}\)+\(\frac{7}{9}\)
= \(\frac{2}{9}\)+ \(\frac{7}{9}\)
= 1
\(\dfrac{2}{9}.\dfrac{5}{17}+\dfrac{7}{9}+\dfrac{2}{9}.\dfrac{12}{17}\\ =\left(\dfrac{2}{9}.\dfrac{5}{17}+\dfrac{2}{9}.\dfrac{12}{17}\right)+\dfrac{7}{9}\\ =\dfrac{2}{9}\left(\dfrac{5}{17}+\dfrac{12}{17}\right)+\dfrac{7}{9}\\ =\dfrac{2}{9}+\dfrac{7}{9}\\ =1\)
\(\dfrac{2}{9}\cdot\dfrac{5}{17}+\dfrac{7}{9}+\dfrac{2}{9}\cdot\dfrac{12}{17}\)
\(=\dfrac{2}{9}\left(\dfrac{5}{17}+\dfrac{12}{17}\right)+\dfrac{7}{9}\)
\(=\dfrac{2}{9}+\dfrac{7}{9}=1\)