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H9
HT.Phong (9A5)
CTVHS
5 tháng 3 2023
A)\(\dfrac{7}{20}-\left(\dfrac{5}{8}-\dfrac{2}{5}\right)\)
\(=\dfrac{7}{20}-\left(\dfrac{25}{40}-\dfrac{16}{40}\right)\)
\(=\dfrac{7}{20}-\dfrac{9}{40}\)
\(=\dfrac{14}{40}-\dfrac{9}{40}=\dfrac{5}{40}=\dfrac{1}{8}\)
B) \(\dfrac{5}{6}+\left(\dfrac{5}{9}-\dfrac{1}{4}\right)\)
\(=\dfrac{5}{6}+\left(\dfrac{20}{36}-\dfrac{9}{36}\right)\)
\(=\dfrac{5}{6}+\dfrac{11}{36}\).
\(=\dfrac{30}{36}+\dfrac{11}{36}=\dfrac{41}{36}\)
C) \(\dfrac{9}{10}-\left(\dfrac{2}{5}-\dfrac{3}{10}\right)+\dfrac{7}{20}\)
\(=\dfrac{9}{10}-\left(\dfrac{4}{10}-\dfrac{3}{10}\right)+\dfrac{7}{20}\)
\(=\dfrac{9}{10}-\dfrac{1}{10}+\dfrac{7}{20}\)
\(=\dfrac{18}{20}-\dfrac{2}{20}+\dfrac{7}{20}=\dfrac{23}{20}\)
5 tháng 3 2023
a: =7/20-5/8+2/5
=14/40-25/40+16/40
=5/40=1/8
b: =5/6+5/9-1/4
=30/36+20/36-9/36
=41/36
c: =9/10-2/5+3/10+7/20
=12/10-2/5+7/20
=7/20+6/5-2/5
=7/20+4/5
=7/20+16/20
=23/20
CD
4
KT
3
TN
6
14 tháng 4 2022
a: =84/12+9/12-10/12=83/12
b: =32/5x7/6=224/30=112/15
c: =6/12+8/12+9/12=23/12
d: =16/20+25/20+7/20=48/20=12/5
28 tháng 3 2023
Bài 1: Tính
a, 1/2 x 2/3 x 3/4 = 1/4
b, 7/8 x 8/9 x 9/10 = 7/10
c, 5/14 x 7/15 x 28/7 = 2/3
d, 2 x 1/2 x 3 x 1/3 x 4 x 1/4 x 5 x 1/5 = 1
Bài 2: Tính
a, 7/20 - ( 5/8 - 3/5 ) = 7/20 - 1/40 = 14/40 - 1/40 = 13/40
b, 5/6 + ( 5/9 - 1/4 ) = 5/6 + 11/36 = 30/36 + 11/36 = 41/36
c, 9/10 - ( 2/5 + 3/10 ) + 7/20 = 9/10 - 7/10 + 7/20 = 2/10 + 7/20 = 4/20 + 7/20 = 11/20.
Bài 3: Tìm x:
a, 1/2 + x = 5/6
x = 5/6 - 1/2
x = 1/3
b, 5/6 - x = 1/3
x = 5/6 - 1/3
x = 1/2
c, x - 1/mấy vậy bạn
d, 1/3 x x = 1/6
x = 1/6 : 1/3
x = 1/2
17 tháng 4 2022
1) 1/3 x 1/2 x 3/7 = 1/6 x 3/7 = 1/14
2) 5/4 x 1/3 + 1/7 = 5/12 + 1/7 = 47/84
3) 8 x (8/9 - 2/3) = 8 x 2/9 = 16/9
4) 5/6 x 48/20 x 1/2 = 2 x 1/2 = 1
5) (2/5 + 3/4) x 8 = 23/20 x 8 = 46/5
6) 10 x (1/2 - 1/5) = 10 x 3/10 = 3
GL
24 tháng 8 2023
a) \(\dfrac{2}{5}=\dfrac{2\times3}{5\times3}=\dfrac{6}{15}=\dfrac{2}{5}\)
\(\dfrac{4}{7}=\dfrac{4\times2}{7\times2}=\dfrac{8}{14}=\dfrac{4}{7}\)
\(\dfrac{13}{54}=\dfrac{13\times3}{54\times3}=\dfrac{39}{162}=\dfrac{13}{54}\)
b) \(\dfrac{8}{20}=\dfrac{8:4}{20:4}=\dfrac{2}{5}\)
\(\dfrac{10}{16}=\dfrac{10:2}{16:2}=\dfrac{5}{8}\)
\(\dfrac{25}{65}=\dfrac{25:5}{65:5}=\dfrac{5}{13}\)
LH
2
8 tháng 3 2018
a) \(\frac{7}{20}-\left(\frac{5}{8}-\frac{2}{5}\right)=\frac{7}{20}-\left(\frac{25}{40}-\frac{16}{40}\right)=\frac{7}{20}-\frac{9}{40}=\frac{14}{40}-\frac{9}{40}=\frac{3}{20}\)
b) \(\frac{5}{6}-\left(\frac{5}{9}-\frac{1}{4}\right)=\frac{5}{6}-\left(\frac{50}{36}-\frac{9}{36}\right)=\frac{5}{6}-\frac{41}{36}=\frac{30}{36}-\frac{41}{36}=-\frac{11}{36}\)
c) \(\frac{9}{10}-\left(\frac{2}{5}+\frac{3}{10}\right)+\frac{7}{20}\)
\(=\frac{9}{10}-\frac{2}{5}+\frac{3}{10}+\frac{7}{20}\)
\(=\frac{18}{20}-\frac{8}{20}+\frac{6}{20}+\frac{7}{20}\)
\(=\frac{23}{20}\)
Mình làm vội nên không chắc nhé ! Nhưng lớp 4 chưa học số ân thật .
8 tháng 3 2018
a.7/20-(5/8-2/5) b.5/6-(5/9-1/4) c.9/10-(2/5+3/10)+7/20
=7/20-9/40 =5/6-11/36 =9/10-7/10+7/20
=5/40=1/8 =19/36 =2/10+7/20
=11/20
\(\frac{7}{20}+\left(\frac{5}{8}-\frac{2}{5}\right)\)
\(=\frac{7}{20}+\frac{9}{40}\)
\(=\frac{23}{40}\)
Hc tốt
\(\frac{7}{20}+\left(\frac{5}{8}-\frac{2}{5}\right)\)
\(=\frac{7}{20}+\left(\frac{25}{40}-\frac{16}{40}\right)\)
\(=\frac{7}{20}+\frac{9}{40}\)
\(=\frac{14}{40}+\frac{9}{40}\)
\(=\frac{16}{40}\)
\(=\frac{2}{5}\)