tính bằng cách thuân tiện nhất 2 phần 3 nhaan4 phần 7cộng 2 phần 3 nhân 3 phần 7
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ND
0
NT
4
11 tháng 3 2017
\(\frac{1}{3}x\)\(\frac{1}{2}-\frac{1}{5}x\)\(\frac{1}{2}\)
=(\(\frac{1}{3}-\frac{1}{5}\)) x \(\frac{1}{2}\)
=\(\frac{2}{15}x\)\(\frac{1}{2}\)
=\(\frac{1}{15}\)
11 tháng 3 2017
1/3 * 1/2 - 1/5 * 1/2
= (1/3 + 1/5) * 1/2
=8/15*1/2
=4/15
31 tháng 7 2021
\(\dfrac{3}{4}.\dfrac{2}{3}-\dfrac{1}{6}.\dfrac{3}{4}-\dfrac{3}{4}.\dfrac{1}{2}\)
= \(\dfrac{3}{4}.\left(\dfrac{2}{3}-\dfrac{1}{6}-\dfrac{1}{2}\right)\)
= \(\dfrac{3}{4}.0\)
= 0
31 tháng 7 2021
\(\dfrac{3}{4}\cdot\dfrac{2}{3}-\dfrac{1}{6}\cdot\dfrac{3}{4}-\dfrac{3}{4}\cdot\dfrac{1}{2}\)
\(=\dfrac{3}{4}\left(\dfrac{2}{3}-\dfrac{1}{6}-\dfrac{1}{2}\right)\)
\(=\dfrac{3}{4}\cdot\left(\dfrac{4}{6}-\dfrac{1}{6}-\dfrac{3}{6}\right)\)
=0
11 tháng 4 2016
1/10+2/20+3/30+4/40+5/50+6/60+7/70+8/80+9/90
=1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10
=1/10 x 9 = 9/10
11 tháng 4 2016
=7/70+7/70+7/70+7/70+7/70+7/70+7/70+7/70+7/70
=7/70*9/9
=63/630=1/10
NT
3
11 tháng 3 2017
\(\frac{5}{5}x\)\(\frac{17}{21}+\frac{17}{21}x\)\(\frac{2}{5}\)
=(\(\frac{5}{5}+\frac{2}{5}\)) x\(\frac{17}{21}\)
=\(\frac{7}{5}x\)\(\frac{17}{21}\)
\(\frac{119}{105}\)
NT
1
30 tháng 4 2023
3/5 x 5 + 12 x 3/5 + 3 : 5/3
=3/5 x 5 + 12 x 3/5 + 3 x 3/5
= 3/5 x ( 5 + 12 + 3 )
= 3/5 x 20
= 12
UT
16 tháng 4 2021
\(a.32,5-3\cdot0,87=32,5-2,61=29,89\)
\(8,5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8,5\cdot\left(\dfrac{3}{2}+\dfrac{4}{4}\right):5\\ =8,5\cdot\left(\dfrac{6}{4}+\dfrac{4}{4}\right):5\\ =8,5\cdot\dfrac{10}{4}:5\\ =\dfrac{85}{4}:5\\ =\dfrac{17}{4}\)
\(b.30,96-6,45+14,4:3=30,96-6,45+4,8\\ =29,31\)
\(\dfrac{2}{5}\cdot\left(\dfrac{4}{5}-\dfrac{1}{2}\right)=\dfrac{2}{5}\cdot\left(\dfrac{8}{10}-\dfrac{5}{10}\right)\\ =\dfrac{2}{5}\cdot\dfrac{3}{10}=\dfrac{3}{25}\)
bài 2
\(a.2,5\cdot12,5\cdot8\cdot0,4=\left(2,5\cdot0,4\right)\left(12,5\cdot8\right)\\ =1\cdot100=100\)
b,\(\dfrac{12}{15}\cdot\dfrac{5}{6}\cdot\dfrac{3}{20}\cdot\dfrac{32}{5}=\dfrac{12\cdot5\cdot3\cdot32}{15\cdot6\cdot20\cdot5}\\ =\dfrac{3\cdot4\cdot5\cdot3\cdot4\cdot8}{3\cdot5\cdot2\cdot3\cdot5\cdot4\cdot5}=\dfrac{16}{25}\)
16 tháng 4 2021
Bài 1:
a) \(32.5-3\cdot0.87=32.5-2.61=29.89\)
\(8.5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8.5\cdot\dfrac{5}{2}:5=\dfrac{17}{2}\cdot\dfrac{5}{2}:5=\dfrac{85}{4}\cdot\dfrac{1}{5}=\dfrac{17}{4}\)
LL
3
30 tháng 4 2018
\(\frac{5}{12}\times\frac{2}{3}+\frac{2}{3}\times\frac{7}{12}+\frac{1}{3}\)
\(=\frac{2}{3}\times\left(\frac{5}{12}+\frac{7}{12}\right)+\frac{1}{3}\)
\(=\frac{2}{3}\times1+\frac{1}{3}\)
\(=\frac{2}{3}+\frac{1}{3}\)
\(=1\)
30 tháng 4 2018
\(\frac{5}{12}\times\frac{2}{3}+\frac{2}{3}\times\frac{7}{12}+\frac{1}{3}=\frac{2}{3}\times\left(\frac{5}{12}+\frac{7}{12}\right)+\frac{1}{3}\)
\(=\frac{2}{3}\times\frac{12}{12}+\frac{1}{3}=\frac{2}{3}\times1+\frac{1}{3}=\frac{2}{3}+\frac{1}{3}=\frac{3}{3}=1\)
MS
23 tháng 4 2018
\(\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{4}{6}+\frac{9}{12}+\frac{16}{20}\)
\(=\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{2}{3}+\frac{3}{4}+\frac{4}{5}\)
\(=\left(\frac{1}{3}+\frac{2}{3}\right)+\left(\frac{1}{4}+\frac{3}{4}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)\)
\(=\frac{3}{3}+\frac{4}{4}+\frac{5}{5}\)
\(=1+1+1\)
\(=3\)
C
20 tháng 1
\(\dfrac{1}{3}+\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{4}{6}+\dfrac{9}{12}+\dfrac{16}{20}\)
\(=\dfrac{1}{3}+\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{2}{3}+\dfrac{3}{4}+\dfrac{4}{5}\)
\(=\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\left(\dfrac{1}{4}+\dfrac{3}{4}\right)+\left(\dfrac{1}{5}+\dfrac{4}{5}\right)\)
\(=\dfrac{3}{3}+\dfrac{4}{4}+\dfrac{5}{5}\)
\(=1+1+1=3\)
\(\frac{2}{3}\cdot\frac{4}{7}+\frac{2}{3}\cdot\frac{3}{7}\)
=\(\frac{2}{3}\left(\frac{4}{7}+\frac{3}{7}\right)\)
= \(\frac{2}{3}\cdot1\)
= \(\frac{2}{3}\)