`2/5 + 9/15= 2/5 + 3/5=5/5=1`

`15/45 + 25/30= 1/3 + 5/6= 2/6+5/6=7/6`

`28/32 + 45/72=7/8+ 5/8=12/8=3/2`

`8/28 + 5/30= 2/7 + 1/6= 12/42 + 7/42= 19/42`

hỏi chơi à?

4/5*5/24*1 và 1/7

miru

Rút gọn rồi tính: 

\(\frac{28}{35}.\frac{15}{72}.1\frac{7}{49}\)

\(=\frac{4}{5}.\frac{5}{24}.\frac{56}{49}\)

\(=\frac{4.5.8}{5.24.7}=\frac{4}{21}\)

\(\frac{28}{35}.\frac{15}{72}.1\frac{7}{49}\)

\(=\frac{4}{5}.\frac{5}{24}.\frac{7}{49}\)

\(=\frac{4}{21}\)

k mk nha, cảm ơn những người đã k

a]27/45+25/15=3/5+5/3=34/15

b]28/32+45/72=7/8+5/8=12/8=3/2

c]8/28+5/30=2/7+1/6=19/42

Câu 1: \(\frac{17}{51}\)x \(\frac{45}{30}\)= \(\frac{1}{3}\)x \(\frac{3}{2}\)

                                   = \(\frac{1}{2}\).

Câu 2: \(\frac{24}{15}\)x \(\frac{56}{72}\)x \(\frac{10}{14}\)= \(\frac{8}{5}\)x \(\frac{7}{9}\)x \(\frac{5}{7}\)

                                                 = \(\frac{56}{45}\)x \(\frac{5}{7}\)

                                                 = \(\frac{8}{9}\)

Câu 3: \(\frac{32}{48}\times\frac{35}{21}\times\frac{63}{14}\times\frac{9}{30}=\frac{2}{3}\times\frac{5}{3}\times\frac{9}{2}\times\frac{3}{10}=\frac{3}{2}\)

k nha

a)17/51x45/40=1/3x3/2=3/6=1/2

b)24/15x56/72x10/14=8/5x7/9x5/7=8/9

c)32/48x35/21x63/14x9/30=2/3x5/3x9/2x3/10=3/2

x x 134 -x x24 -x x 10 = x x ( 134 - 24 - 10)

x = x x 100

x = 1300 : 100

x = 13

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

xin lỗi làm nhầm

45-58+(-45)+(+58)-3=45-58-45+58-3=(45-45)+(58-58)-3=-3

(-57)-(-12)+3-(-57)=-57+12+3+57=(-57+57)+12+3=15

-(-24)-(-30)+(-24)-30+8=24+30-24-30+8=(24-24)+(30-30)+8=8

-(-12)+(+19)-(+12)+8-19=12+19-12+8-19=(12-12)+(19-19)+8=8

47-(-53)+(-47)-(+53)=47+53-47-53=(47-47)+(53-53)=0

-(+28)+32-(-28)+(-34)=-28+32+28-34=(-28+28)-(34-32)=-2

15-(+72)+(-15)+(+72)=15-72-15+72=(15-15)+(72-72)=0

20-(+46)+(-25)-(-46)=20-46-25+46=(20-25)+(46-46)=-5

28-(-32)+(-28)-32+5=28+32-28-32+5=(28-28)+(32-32)+5=5

-75+(-49)+(+75)+49-12=-75-49+75+49-12=(-75+75)+(49-49)-12=-12

\(...=45-58-45+58-3=-3\)

\(...=-57+12+3+57=15\)

\(...=24+30-24-30+8=8\)

\(...=12+19-12+8-19=8\)

\(...=47+53-47-53=0\)

\(...=-28+32+28-34=-2\)

\(...=15-72-15+72=0\)

\(...=20-46-25+46=-5\)

\(=...28+32-28-32+5=5\)

\(...=-75-49+75+49-12=-12\)

a) \(\frac{2}{5}+\frac{9}{15}=\frac{2}{5}+\frac{3}{5}=\frac{5}{5}=1\)

b) \(\frac{15}{45}+\frac{25}{30}=\frac{1}{3}+\frac{5}{6}=\frac{2}{6}+\frac{5}{6}=\frac{7}{6}\)

c) \(\frac{28}{32}+\frac{45}{72}=\frac{7}{8}+\frac{5}{8}=\frac{12}{8}=\frac{3}{2}\)

d) \(\frac{8}{28}+\frac{5}{30}=\frac{2}{7}+\frac{1}{6}=\frac{12}{42}+\frac{7}{42}=\frac{19}{42}\)

a) \(\frac{2}{5}+\frac{9}{15}\)=\(\frac{2}{5}+\frac{3}{5}=\frac{2+3}{5}=1\)

b)\(\frac{15}{45}+\frac{25}{30}=\frac{1}{3}+\frac{5}{6}=\frac{2}{6}+\frac{5}{6}=\frac{2+5}{6}=\frac{7}{6}\)

c)\(\frac{28}{32}+\frac{45}{72}=\frac{7}{8}+\frac{5}{8}=\frac{7+5}{8}=\frac{12}{8}=\frac{3}{2}\)

d)\(\frac{8}{28}+\frac{5}{30}=\frac{2}{7}+\frac{1}{6}=\frac{12}{42}+\frac{7}{42}=\frac{12+7}{42}=\frac{19}{42}\)

mn ơi e vít nhầm là tính rồi rút gọn mn sửa lại là rút gọn rùi tính

a: =2/5+3/5=1

b: =1/3+5/6=2/6+5/6=7/6

c: =7/8+5/8=12/8=3/2

d: =2/3+2/10

=20/30+6/30

=26/30=13/15

e: =1/2+1/3

=3/6+2/6

=5/6

f: =2/7+1/6

=12/42+7/42

=19/42

a: =2/5+3/5=1

b: =1/3+2/3=1

c: =7/8+5/8=12/8=3/2

d: =2/7+3/7=5/7

\(a,\dfrac{2}{5}+\dfrac{3}{5}=\dfrac{5}{5}=1\\ b,\dfrac{1}{3}+\dfrac{2}{3}=\dfrac{3}{3}=1\\ c,\dfrac{7}{8}+\dfrac{5}{8}=\dfrac{12}{8}=\dfrac{3}{2}\\ d,\dfrac{1}{7}+\dfrac{3}{7}=\dfrac{4}{7}\)

a) 2/5+ 3/5= 5/5=1

b) 1/3+2/3=3/3=1

c) 7/8+5/8= 12/8=3/2

d) 2/7+3/7=5/7