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tính = cách thuận tiện nhất
a/ 5/11 nhân 7/25 trừ 15/11 nhân 1/5
b/ 3/7 nhân 25/19 trừ 1/7 nhân 18/19
a ) \(\frac{5}{11}\times\frac{7}{25}\times\frac{15}{11}\times\frac{1}{5}\)
\(=\frac{5\times7\times15\times1}{11\times25\times11\times5}\)
\(=\frac{1\times7\times3\times1}{11\times5\times11\times1}\)
\(=\frac{21}{\left(10\times5+5\times1\right)\times11}\)
\(=\frac{21}{55\times11}\)
\(=\frac{21}{55\times10+55}\)
\(=\frac{21}{550+55}\)
\(=\frac{21}{605}\) ( quá đơn giản )
\(\)
A) \(\frac{5}{11}\times\frac{7}{25}-\frac{15}{11}\times\frac{1}{5}\)
\(=\frac{5\times7}{11\times25}-\frac{15\times1}{11\times5}\)
\(=\frac{35}{10\times25+25}-\frac{15}{55}\)
\(=\frac{35}{250+25}-\frac{15}{55}\)
\(=\frac{35}{275}-\frac{15}{55}\)
\(=\frac{7}{55}-\frac{15}{55}\)
\(=\frac{7-15}{55}\)
\(=\frac{-8}{55}\)
\(\frac{1}{3}x\)\(\frac{1}{2}-\frac{1}{5}x\)\(\frac{1}{2}\)
=(\(\frac{1}{3}-\frac{1}{5}\)) x \(\frac{1}{2}\)
=\(\frac{2}{15}x\)\(\frac{1}{2}\)
=\(\frac{1}{15}\)
1/3 * 1/2 - 1/5 * 1/2
= (1/3 + 1/5) * 1/2
=8/15*1/2
=4/15
a) 395 x 15 + 85 x 395
= 395 x ( 85 + 15 )
= 395 x 100
= 39500
b) 1357 x 28 + 73 x 1357 - 1357
= 1357 x 28 + 73 x 1357 - 1357 x 1
= = 1357 x ( 28 + 73 - 1)
= 1357 x 100
= 135700
\(\dfrac{3}{4}.\dfrac{2}{3}-\dfrac{1}{6}.\dfrac{3}{4}-\dfrac{3}{4}.\dfrac{1}{2}\)
= \(\dfrac{3}{4}.\left(\dfrac{2}{3}-\dfrac{1}{6}-\dfrac{1}{2}\right)\)
= \(\dfrac{3}{4}.0\)
= 0
\(\dfrac{3}{4}\cdot\dfrac{2}{3}-\dfrac{1}{6}\cdot\dfrac{3}{4}-\dfrac{3}{4}\cdot\dfrac{1}{2}\)
\(=\dfrac{3}{4}\left(\dfrac{2}{3}-\dfrac{1}{6}-\dfrac{1}{2}\right)\)
\(=\dfrac{3}{4}\cdot\left(\dfrac{4}{6}-\dfrac{1}{6}-\dfrac{3}{6}\right)\)
=0
819 x 16 - 819 x 5 - 819
= 819 x 16 - 819 x 5 - 819 x 1
= 819 x ( 16 - 5 - 1 )
= 819 x 10
= 819
2014 + 2014 x 2 + 7 x 2014
= 2014 x (1 + 2 + 7)
= 2017 x 10
= 20170
2014 + 2014 x 2 + 7 x 2014
= 2014 + 2014 x 2 + 7 + 2014 +1
= 2014 x ( 7 + 2 + 1 )
= 2014 x 10
= 20140
2014 + 2014 x 2 + 2014 x 7
=2014 x (1 + 2 + 7)
=2014 x 10
=20140
476 x (34267 - 28765 )
=476 x 5502
=2618952
kb nhé
a ,=2014 x 1 + 2014x2 + 2014 x 7
= 2014 x ( 1+2+7)
= 2014 x 10
= 20140
b, =2623236
(ko tính thuận tiện đc)
\(2014+2014\times2+7\times2014\)
\(=2014(1+2+7)\)
\(=2014\times10\)
\(=20140\)
Các bạn xem lai giúp mình đi😔😔
Tính bằng cách thuận tiện :
2014 + 2014 × 2 + 7 × 2014
= 2014 × 1 + 2014 × 2 + 7 × 2014
= 2014 × ( 1 + 2 + 7 )
= 2014 × ( 3 + 7 )
= 2014 × 10
= 20 140
b. 476(34267-28756) = 476(30.000 + 4267 -30.000 + 1244)= 476 x 5511=4.(100+10+10-1)(5000+500+10+1)
=4. (500.000+50.000+1.000+100 + 50.000 + 5.000+100+10 + 50.000 + 5000+100 +10 - 5000-500-10-1)
=4 (500.000 + 150.000 + 6000 - 191)= 2.000.000 + 600.000 + 24.000 - 4x191 = 2.624.000 -4.200 + 4.9)
=2.624.000-800+36=2.623.200+36=2623236