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\(\dfrac{2}{5}+\dfrac{4}{5}:4=\dfrac{2}{5}+\dfrac{1}{5}=\dfrac{3}{5}\)
\(\dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}=\dfrac{3}{8}\left(\dfrac{7}{4}-1\right)=\dfrac{3}{8}\times\dfrac{3}{4}=\dfrac{9}{32}\)
\(\dfrac{6}{5}-3:\dfrac{15}{4}=\dfrac{6}{5}-\dfrac{4}{5}=\dfrac{2}{5}\)
\(=\dfrac{2}{5}+\dfrac{4}{5}\times\dfrac{1}{4}\\ =\dfrac{2}{5}+\dfrac{1}{5}\\ =\dfrac{3}{5}\\ \\ =\dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}\times1\\ =\dfrac{3}{8}\times\left(\dfrac{7}{4}-1\right)\\ =\dfrac{3}{8}\times\dfrac{3}{4}\\ =\dfrac{9}{32}\\\\ =\dfrac{6}{5}-3\times\dfrac{4}{15}\\ =\dfrac{6}{5}-\dfrac{4}{5}\\ =\dfrac{2}{5}\)
\(\frac{3}{8}+\frac{15}{32}=\frac{12}{32}+\frac{15}{32}=\frac{27}{32}\)
\(\frac{8}{9}-\frac{5}{36}=\frac{32}{36}-\frac{5}{36}=\frac{27}{36}=\frac{3}{4}\)
\(\frac{15}{6}-\frac{7}{4}+2=\frac{30}{12}-\frac{28}{12}+\frac{24}{12}=\frac{26}{12}=\frac{13}{6}\)
\(3-\left(\frac{3}{4}+\frac{5}{12}\right)=3-\left(\frac{9}{12}+\frac{5}{12}\right)=3-\frac{14}{12}=3-\frac{7}{6}=\frac{18}{6}-\frac{7}{6}=\frac{11}{6}\)
a) (15 +35) : 5 = ?
Cách 1: (15 +35) : 5
= 50 : 5 = 10
Cách 2: (15 +35) : 5
= 15 : 5 + 35 : 5
= 3 + 7 = 10
+) (80 +4) : 4 = ?
Cách 1:(80 +4) : 4
= 84 : 4 = 21
Cách 2:(80 +4) : 4
= 80 : 4 + 4 :4 = 20 +1 = 21
b) 18 : 6 + 24 : 6 = ?
Cách 1: 18 : 6 + 24 : 6
= 3 + 4 = 7
Cách 2: (18 + 24) : 6
= 42 : 6 = 7
+) 60 : 3 + 9 : 3 =?
Cách 1: 60 : 3 + 9 : 3
= 20 + 3 = 23
Cách 2: 60 : 3 + 9 : 3
=(60 +9) : 3 = 23
a) (15 +35) : 5 = ?
Cách 1: (15 +35) : 5
= 50 : 5 = 10
Cách 2: (15 +35) : 5
= 15 : 5 + 35 : 5
= 3 + 7 = 10
+) (80 +4) : 4 = ?
Cách 1:(80 +4) : 4
= 84 : 4 = 21
Cách 2:(80 +4) : 4
= 80 : 4 + 4 :4 = 20 +1 = 21
b) 18 : 6 + 24 : 6 = ?
Cách 1: 18 : 6 + 24 : 6
= 3 + 4 = 7
Cách 2: (18 + 24) : 6
= 42 : 6 = 7
+) 60 : 3 + 9 : 3 =?
Cách 1: 60 : 3 + 9 : 3
= 20 + 3 = 23
Cách 2: 60 : 3 + 9 : 3
=(60 +9) : 3 = 23
HT5/4 < 5/3
19/24 < 1
43/43 = 1
47/35 > 1
3/5 < 21
134/135 > 125/126
9/4 > 11/6
a)1+2+3+4+5+6+7+8+9
=(1+9)+(2+8)+(3+7)+(4+6)+5
=10+10+10+10+5
=10x4+5=45
b)8x3+8x7
=8x(3+7)
=8x10=80
c)8x172-8x72
=8x(172-72)
=8x100=800
a. 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 +9
= (1 + 9) + (2 + 8) + (3 + 7) + ( 4 + 6) + 5
= 10 + 10 + 10 + 10 + 5
= 45
\(\frac{1}{4}+\frac{3}{5}=\frac{17}{20}\)
\(\frac{5}{2}+\frac{7}{9}=\frac{59}{18}\)
\(\frac{3}{2}+\frac{2}{3}=\frac{13}{6}\)
\(\frac{4}{5}+\frac{3}{2}=\frac{23}{10}\)
\(\frac{4}{5}+\frac{3}{15}=\frac{4}{5}+\frac{1}{5}=1\)
\(\frac{2}{3}+\frac{32}{24}=\frac{2}{3}+\frac{4}{3}=2\)
\(\frac{5}{6}+\frac{15}{18}=\frac{5}{6}+\frac{5}{6}=\frac{10}{6}=\frac{5}{3}\)
\(\frac{8}{15}+\frac{2}{3}=\frac{8}{15}+\frac{10}{15}=\frac{18}{15}=\frac{6}{5}\)
\(\frac{3}{7}+\frac{4}{8}=\frac{24}{56}+\frac{28}{56}=\frac{52}{56}=\frac{13}{14}\)
_HT_
a)\(=\dfrac{16}{13}-\dfrac{3}{15}+\dfrac{6}{13}=\dfrac{22}{13}-\dfrac{3}{15}=\dfrac{96}{65}\)
b)\(=\dfrac{21}{8}-\left(\dfrac{5}{10}+\dfrac{6}{10}\right)=\dfrac{21}{8}-\dfrac{11}{10}=\dfrac{61}{40}\)
c)\(=\dfrac{27}{10}-3-\dfrac{4}{7}--\dfrac{61}{70}\)
2/3 + 3/4=17/12
9/4 + 3/5=57/20
5/24 + 1/4=11/24
3/15 - 5/35=2/35 18/27 - 2/6=1/3 37/12 - 3=1/12
11/9 x 3/22=1/6 7/13 x 13/7=1 4 x6/7=24/7
2/5 : 3/10=4/3 3/8 : 9/4=1/6 8/21 : 4/7=2/3
\(\dfrac{8}{9}+\dfrac{3}{18}=\dfrac{16}{18}+\dfrac{3}{18}=\dfrac{19}{18}\) \(\dfrac{5}{7}-\dfrac{4}{11}=\dfrac{55}{77}-\dfrac{28}{77}=\dfrac{3}{11}\)
\(\dfrac{3}{4}+\dfrac{4}{5}=\dfrac{15}{20}+\dfrac{16}{20}=\dfrac{21}{20}\) \(\dfrac{5}{7}-\dfrac{3}{5}=\dfrac{25}{35}-\dfrac{21}{35}=\dfrac{4}{35}\)
\(\dfrac{7}{9}X\dfrac{3}{4}=\dfrac{7}{9}X\dfrac{3}{4}=\dfrac{7}{12}\) \(\dfrac{8}{3}X\dfrac{21}{4}=\dfrac{8}{3}X\dfrac{21}{4}=14\)
\(\dfrac{12}{7}:\dfrac{1}{4}=\dfrac{12}{7}X\dfrac{4}{1}=\dfrac{48}{7}\) \(\dfrac{7}{2}:\dfrac{9}{4}=\dfrac{7}{2}X\dfrac{4}{9}=\dfrac{14}{9}\)
a) 2/5+9/5=11/5
b) 15/45+25/30=7/6
c) 28/32+45/72=3/2
d) 8/28+5/30=19/42
bài 2
a) x - 4/5 =4/5 + (3/7+3/5)
x-4/5=4/5+36/35
x-4/5=64/35
x=64/35+4/5
x=92/35
b) x-7/35=4/5
x=4/5+7/35
x=1
nhớ tk m nhé
a = 18/5
b = 3/9 + 5/6 = 6/18 + 25/18 = 31/18
c = 7/8 + 5/8 = 12/8
d = 4/14 + 1/6 = 14/42 + 7/42 = 21/42 -= 7/14
b2
x - 4/5 = 4.5 + ( 3/7 + 3/5 )
x - 4/5 = 49/35
x = 49/35 + 4/5
x = 77/35
x - 7/35 = 4/5
x = 4/5 + 7/35
x = 1
mình ko chắc chắn đâu
mình nghĩ mình làm sai
\(\dfrac{5}{8}+\dfrac{4}{3}=\dfrac{15}{24}+\dfrac{32}{24}=\dfrac{15+32}{24}=\dfrac{47}{24}\)
\(\dfrac{2}{5}+\dfrac{4}{5}:4=\dfrac{2}{5}+\dfrac{1}{5}=\dfrac{2+1}{5}=\dfrac{3}{5}\)
\(\dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}=\dfrac{21}{32}-\dfrac{3}{8}=\dfrac{21-12}{32}=\dfrac{9}{32}\)
\(\dfrac{6}{5}-3:\dfrac{15}{4}=\dfrac{6}{5}-\dfrac{4}{5}=\dfrac{6-4}{5}=\dfrac{2}{5}\)