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a) 4 x 78 x 5
= (4 x 5) x 78
= 20 x 78
= 1560
b) 2 x 99 x 5
= (2 x 5) x 99
= 10 x 99
= 990
\(\dfrac{14}{9}\) x \(\dfrac{11}{8}-\dfrac{3}{8}\) x \(\dfrac{14}{9}\)
\(=\dfrac{14}{9}\) x \(\left(\dfrac{11}{8}-\dfrac{3}{8}\right)\)
\(=\dfrac{14}{9}\) x \(\dfrac{8}{8}=\dfrac{14}{9}\) x \(1\)
\(=\dfrac{14}{9}\)
34 x 28 - 34 x 11 - 7 x 34
= 34 x (28 - 11 - 7)
= 34 x 10
= 340
Tính bằng cách thuận tiện nhất:
9/4 x 15/11 + 3/4 : 11/7 - 3/4 x 8/11
[Lưu ý trình bày cách làm ra!]
\(\dfrac{9}{4}\times\dfrac{15}{11}+\dfrac{3}{4}:\dfrac{11}{7}-\dfrac{3}{4}\times\dfrac{8}{11}\)
\(=\dfrac{3}{4}\times3\times\dfrac{15}{11}+\dfrac{3}{4}\times\dfrac{7}{11}-\dfrac{3}{4}\times\dfrac{8}{11}\)
\(=\dfrac{3}{4}\times\dfrac{45}{11}+\dfrac{3}{4}\times\dfrac{7}{11}-\dfrac{3}{4}\times\dfrac{8}{11}\)
\(=\dfrac{3}{4}\times\left(\dfrac{45}{11}+\dfrac{7}{11}-\dfrac{8}{11}\right)\)
\(=\dfrac{3}{4}\times4\)
\(=3\)
`9/4xx15/11+3/4:11/7-3/4xx8/11`
`=3/4xx15/11xx3+3/4xx7/11-3/4xx8/11`
`=3/4xx45/11+3/4xx7/11-3/4xx8/11`
`=3/4xx(45/11+7/11-8/11)`
`=3/4xx4`
`=3`
Bạn tham khảo nhé!
a,
97345 - 9205 x 3 + 7 x 9205
= 97345 - 9205 x (3 + 7)
= 97345 - 9205 x 10
= 97345 - 92050
= 5295
b,
4237-237x4+6x237
= 4237- 237x (4+6)
= 4237- 237x 10
= 4237- 2370
= 1867
a.\(\dfrac{18}{15}+\dfrac{7}{15}+\dfrac{12}{15}=\dfrac{18+7+12}{15}=\dfrac{37}{15}\)
b.\(\dfrac{9}{7}+\dfrac{8}{7}+\dfrac{11}{7}=\dfrac{9+8+11}{7}=\dfrac{28}{7}=4\)
a ) \(\frac{7}{11}+\frac{3}{4}+\frac{4}{11}+\frac{1}{4}\)
\(=\left(\frac{7}{11}+\frac{4}{11}\right)+\left(\frac{3}{4}+\frac{1}{4}\right)\)
\(=\frac{11}{11}+\frac{4}{4}\)
\(=1+1\)
\(=2\)
b ) \(\frac{72}{99}-\frac{28}{99}-\frac{14}{99}\)
\(=\frac{72}{99}-\left(\frac{28}{99}+\frac{14}{99}\right)\)
\(=\frac{72}{99}-\frac{42}{99}\)
\(=\frac{30}{99}\)
c ) \(69,78+35,97+30,22\)
\(=\left(69,78+30,22\right)+35,97\)
\(=100+35,97\)
\(=135,97\)
d ) \(83,45-30,98-42,47\)
\(=83,45-\left(30,98+42,47\right)\)
\(=83,45-73,45\)
\(=10\)
Chúc bạn học tốt !!!