4/9:2 ; 3/5:2 ;10/21:5 ;6/7:3
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5 + 4 = 9 1 + 6 = 7 4 + 2 = 6 9 + 1 = 10 2 + 7 = 9
9 - 5 = 4 7 - 1 = 6 6 - 4 = 2 10 - 9 = 1 9 - 2 = 7
9 - 4 = 5 7 - 6 = 1 6 - 2 = 4 10 - 1 = 9 9 - 7 = 2
8 + 1 = 9 7 + 2 = 9 6 + 3 = 9 5 + 4 = 9
1 + 8 = 9 2 + 7 = 9 3 + 6 = 9 4 + 5= 9
9 - 8 = 1 9 - 7 = 2 9 - 6 = 3 9 - 5 = 4
9 - 1 = 8 9 - 2 = 7 9 - 3 = 6 9 - 4 = 5
Lời giải chi tiết:
9 – 3 – 2 = 4 | 9 – 4 – 5 = 0 | 9 – 6 – 2 = 1 |
9 – 4 – 1 = 4 | 9 – 8 – 0 = 1 | 9 – 2 – 7 = 0 |
a) \(\dfrac{5}{7}\times\dfrac{5}{9}+\dfrac{4}{9}\times\dfrac{5}{7}\)
\(=\dfrac{5}{7}\times\left(\dfrac{4}{9}+\dfrac{5}{9}\right)\)
\(=\dfrac{5}{7}\times1\)
\(=\dfrac{5}{7}\)
b) \(\dfrac{1}{10}+\dfrac{5}{9}+\dfrac{4}{9}+\dfrac{9}{10}-1\)
\(=\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\left(\dfrac{1}{10}+\dfrac{9}{10}-1\right)\)
\(=1+0\)
\(=1\)
c) \(\dfrac{5}{7}\times\dfrac{5}{9}+\dfrac{4}{9}\times\dfrac{5}{7}+\dfrac{2}{7}\)
\(=\dfrac{5}{7}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\dfrac{2}{7}\)
\(=\dfrac{5}{7}+\dfrac{2}{7}\)
\(=1\)
d) \(\dfrac{2}{7}+\dfrac{2}{8}+\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{4}{7}\)
\(=\left(\dfrac{2}{8}+\dfrac{1}{4}\right)+\left(\dfrac{2}{7}+\dfrac{1}{7}+\dfrac{4}{7}\right)\)
\(=\left(\dfrac{1}{4}+\dfrac{1}{4}\right)+1\)
\(=\dfrac{1}{2}+1\)
\(=\dfrac{3}{2}\)
e) \(\dfrac{4}{5}+\dfrac{3}{10}+\dfrac{2}{10}+0,7\)
\(=\dfrac{4}{5}+\dfrac{5}{10}+\dfrac{7}{10}\)
\(=\dfrac{4}{5}+\dfrac{12}{10}\)
\(=\dfrac{4}{5}+\dfrac{6}{5}\)
\(=\dfrac{10}{5}\)
\(=2\)
g) \(362\times728+326\times272\)
\(=326\times\left(728+272\right)\)
\(=326\times1000\)
\(=326000\)
3 × 4 = 12 | 2 × 6 = 12 | 4 × 3 = 12 | 5 × 6 = 30 |
3 × 7 = 21 | 2 × 8 = 16 | 4 × 7 = 28 | 5 × 4 = 20 |
3 × 5 = 15 | 2 × 4 = 8 | 4 × 9 = 36 | 5 × 7 = 35 |
3 × 8 = 24 | 2 × 9 = 18 | 4 × 4 = 16 | 5 × 9 = 45 |
Lời giải chi tiết:
1 + 8 = 9 | 2 + 7 = 9 | 3 + 6 = 9 | 4 + 5 = 9 |
8 + 1 = 9 | 7 + 2 = 9 | 6 + 3 = 9 | 5 + 4 = 9 |
9 – 8 = 1 | 9 – 7 = 2 | 9 – 6 = 3 | 9 – 5 = 4 |
9 – 1 = 8 | 9 – 2 = 7 | 9 – 3 = 6 | 9 – 4 = 5 |
\(\dfrac{4}{9}:2=\dfrac{4}{9}.\dfrac{1}{2}=\dfrac{2}{9}\)
\(\dfrac{3}{5}:2=\dfrac{3}{5}.\dfrac{1}{2}=\dfrac{3}{10}\)
\(\dfrac{10}{21}:5=\dfrac{10}{21}.\dfrac{1}{5}=\dfrac{2}{21}\)
\(\dfrac{6}{7}:3=\dfrac{6}{7}.\dfrac{1}{3}=\dfrac{2}{7}\)