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\(a,\dfrac{1}{3}+\dfrac{3}{4}\times\dfrac{2}{9}=\dfrac{1}{3}+\dfrac{6}{36}=\dfrac{1}{3}+\dfrac{1}{6}=\dfrac{2}{6}+\dfrac{1}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)
\(b,2-\left(\dfrac{2}{5}+\dfrac{2}{3}\right)=2-\left(\dfrac{6}{15}+\dfrac{10}{15}\right)=2-\dfrac{16}{15}=\dfrac{30}{15}-\dfrac{16}{15}=\dfrac{14}{15}\)
\(c,\dfrac{2}{5}:\dfrac{4}{7}+\dfrac{1}{3}=\dfrac{2}{5}\times\dfrac{7}{4}+\dfrac{1}{3}=\dfrac{14}{20}+\dfrac{1}{3}=\dfrac{7}{10}+\dfrac{1}{3}=\dfrac{21}{30}+\dfrac{10}{30}=\dfrac{31}{30}\)
\(d,\dfrac{9}{13}:\dfrac{3}{26}-\dfrac{8}{13}=\dfrac{9}{13}\times\dfrac{26}{3}-\dfrac{8}{13}=\dfrac{234}{39}-\dfrac{8}{13}=6-\dfrac{8}{13}=\dfrac{78}{13}-\dfrac{8}{13}=\dfrac{70}{13}\)
a:=1/3+6/36
=1/3+1/6
=1/2
b: =2-16/15
=14/15
c: =2/5*7/4+1/3
=14/20+1/3
=7/10+1/3
=21/30+10/30=31/30
d: =9/13*26/3-8/13
=3-8/13=31/13
2/5 + 11/15 = 17/15
7/8 - 7/9 = 7/72
11/13 x 26/31 = 22/31
16/24 : 4 = 1/6
30 : 6/5 = 25
9/16 : 4 = 9/64
1/2 : 1/3 x 8/15 = 3/2 x 8/15 = 4/5
a) \(\dfrac{2}{5}+\dfrac{11}{15}=\dfrac{6}{15}+\dfrac{11}{15}=\dfrac{17}{15}\)
b) \(\dfrac{7}{8}-\dfrac{7}{9}=\dfrac{63}{72}-\dfrac{56}{72}=\dfrac{7}{72}\)
c) \(\dfrac{11}{13}\cdot\dfrac{26}{31}=\dfrac{26}{13}\cdot\dfrac{11}{31}=\dfrac{22}{31}\)
d) \(\dfrac{1}{2}:\dfrac{1}{3}\cdot\dfrac{2}{5}=\dfrac{1}{2}\cdot3\cdot\dfrac{2}{5}=\dfrac{3}{5}\)
a,\(\frac{1}{5}\times\frac{2}{9}\div\frac{1}{15}\)
\(=\frac{1}{5}\times\frac{2}{9}\times15\)
\(=\left(\frac{1}{5}\times15\right)\times\frac{2}{9}\)
\(=3\times\frac{2}{9}\)
\(=\frac{2}{3}\)
b\(\frac{4}{15}\times\frac{7}{15}\times\frac{5}{4}\)
\(=\left(\frac{4}{15}\times\frac{5}{4}\right)\times\frac{7}{15}\)
\(=\frac{1}{3}\times\frac{7}{15}\)
\(=\frac{7}{45}\)
c,\(\frac{21}{23}\times\frac{5}{11}\times\frac{44}{?}\)
d,\(26\times\frac{13}{42}\div13\)
\(=\left(26\div13\right)\times\frac{13}{42}\)
\(=2\times\frac{13}{42}\)
\(=\frac{13}{21}\)
a \(\dfrac{6}{15}+\dfrac{11}{15}=\dfrac{17}{15}\)
b \(\dfrac{22}{77}-\dfrac{14}{77}=\dfrac{8}{77}\)
c \(\dfrac{11}{13}\times\dfrac{26}{31}=11\times\dfrac{2}{31}=\dfrac{22}{31}\)
d \(\dfrac{1}{2}\times3\times\dfrac{2}{5}=\dfrac{3}{5}\)
a,Cách 1: (6/11 + 5/11 ) x 3/7 Cách 2 :(6/11 + 5/11) x 3/7
= 1 x 3/7 =6/11 x 3/7 + 5/11 x 3/7
= 3/7 = 18/77 + 15/77
= 3/7
b, Cách 1:3/5 x 7/9 - 3/5 x 2/9 Cách 2 :3/5 x 7/9 - 3/5 x 2/9
= 7/15 - 2/15 = 3/5 x (7/9 - 2/9 )
= 1/3 = 3/5 x 5/9
= 1/3
c, Cách 1:(6/7 - 4/7) : 2/5 Cách 2: ( 6/7- 4/7 ) : 2/5
= 2/7 : 2/5 = 6/7 : 2/5 - 4/7 : 2/5
= 5/7 = 15/7 - 10/7
= 5/7
d,Cách 1:8/15 : 2/11 + 7/15 : 2/11 Cách 2:8/15 : 2/11 +7/15 : 2/11
= 88/30 + 77/30 =(8/15+7/15) :2/11
= 11/2 = 1 : 2/11
= 11/2
Bài 2 cậu tự làm nhé !
một thửa ruộng hình vuông có chu vi là 100 mét.Người ta cấy lúa trung bình là 1 mét vuông thu hoạch được 12/25 kg.hỏi trên thửa ruộng đó người ta thu hoạch được bao nhiêu tạ thóc
a, 7/15 +4/5 =7/15+12/15 = 19/15
b,2/3-3/8=16/24-9/24=7/24
C,4/7x21/16:5/8=4/7x21/16x8/5=6/5
D,13x42x11/33x26x35=1/5
\(C,\dfrac{1}{2}.\dfrac{3}{4}+\dfrac{1}{2}.\dfrac{1}{4}=\dfrac{1}{2}.\left(\dfrac{3}{4}+\dfrac{1}{4}\right)\)
\(=\dfrac{1}{2}.\dfrac{4}{4}=\dfrac{1}{2}.1=\dfrac{1}{2}\)
\(D,\dfrac{11}{3}.\dfrac{26}{7}-\dfrac{26}{7}.\dfrac{8}{3}=\dfrac{26}{7}.\left(\dfrac{11}{3}-\dfrac{8}{3}\right)\)
\(=\dfrac{26}{7}.\dfrac{3}{3}=\dfrac{26}{7}.1=\dfrac{26}{7}\)
a)5/12 + 1/4 = \(\dfrac{5}{12}+\dfrac{3}{12}=\dfrac{8}{12}=\dfrac{2}{3}\)
b)23/5 - 11/3 = \(\dfrac{69}{15}-\dfrac{55}{15}=\dfrac{14}{15}\)
c)4/5 + 13 = \(\dfrac{4}{5}+\dfrac{65}{5}=\dfrac{69}{5}\)
d)8/5 : 1/3 = \(\dfrac{8}{5}x3=\dfrac{24}{5}\)
e)3/7 x 2 =\(\dfrac{6}{7}\)
\(a,\) \(\dfrac{5}{12}+\dfrac{1}{4}=\dfrac{5}{12}+\dfrac{3}{12}=\dfrac{8}{12}=\dfrac{2}{3}\)
\(b,\) \(\dfrac{23}{5}-\dfrac{11}{3}=\dfrac{69}{15}-\dfrac{55}{15}=\dfrac{14}{15}\)
\(c,\) \(\dfrac{4}{5}+\dfrac{1}{3}=\dfrac{12}{15}+\dfrac{5}{15}=\dfrac{17}{15}\)
\(d,\) \(\dfrac{8}{5}:\dfrac{1}{3}=\dfrac{8}{5}\times\dfrac{3}{1}=\dfrac{24}{5}\)
\(e,\) \(\dfrac{3}{7}\times2=\dfrac{3\times2}{7}=\dfrac{6}{7}\)
`(1/2+3/4)xx4`
`=(2/4+3/4)xx4`
`=((2+3)/4)xx4`
`=5/4xx4`
`=20/4`
`=5`
_________________________________
`(5/7-3/14)xx7`
`=(10/14-3/14)xx7`
`=7/14xx7`
`=1/2xx7`
`=7/2`
___________________________
`1/2xx3/4+1/2xx1/4`
`=1/2xx(3/4+1/4)`
`=1/2xx4/4`
`=1/2xx1`
`=1/2`
____________________________
`11/13xx26/5-26/5xx8/13`
`= 26/5 xx ( 11/13 - 8/13)`
`=26/5 xx 3/13`
`=6/5`
a) (1/2+3/4) x4= 5/4x4= 5
b) (5/7-3/14) x7= 1/2 x7= 7/2
c)1/2 x3/4+1/2x1/4= 1/2x (3/4+1/4)= 1/2x1= 1/2