a, \(\frac{7.25-49}{7.24+21}=\frac{7.25-7.7}{7.24+7.3}=\frac{7.\left(25-7\right)}{7.\left(24+3\right)}=\frac{7.18}{7.27}=\frac{7.9.2}{7.9.3}=\frac{2}{3}\)

b, \(\frac{2.\left(-13\right).9.10}{-3.4.\left(-5\right).26}=\frac{2.13.\left(-3\right).3.\left(-2\right).\left(-5\right)}{-3.\left(-2\right).\left(-2\right).\left(-5\right).2.13}=\frac{-3}{2}\)

a)\(\frac{2}{3}\)

b)\(-\frac{3}{2}\)

a)\(\frac{2}{3}\)

b)\(-\frac{3}{2}\)

mn giúp

Này bạn làm sao để ra dấu phân số vậy

b,=1/5-1/7+1/7-1/9+...+1/59-1/61

=1/5-1/61

=54/115

a.\(\dfrac{27}{8}\)

b.\(\dfrac{37}{40}\)
c.\(\dfrac{5}{2}\)

d.\(\dfrac{7}{3}\)

e.5

g.\(\dfrac{53}{16}\)

Bài 1 :

a) \(\dfrac{3}{2}+\dfrac{5}{4}+\dfrac{5}{8}=\dfrac{12}{8}+\dfrac{10}{8}+\dfrac{5}{8}=\dfrac{12+10+5}{8}=\dfrac{27}{8}\)

b) \(\dfrac{4}{5}-\dfrac{3}{8}+\dfrac{2}{4}=\dfrac{32}{40}-\dfrac{15}{40}+\dfrac{20}{40}=\dfrac{32-15+20}{40}=\dfrac{37}{40}\)

c) \(3+\dfrac{6}{8}-\dfrac{5}{4}=\dfrac{3}{1}+\dfrac{6}{8}-\dfrac{5}{4}=\dfrac{24}{8}+\dfrac{6}{8}-\dfrac{10}{8}=\dfrac{20}{8}=\dfrac{5}{2}\)

d) \(\dfrac{5}{6}-\dfrac{1}{2}+2=\dfrac{5}{6}-\dfrac{1}{2}+\dfrac{2}{1}=\dfrac{5}{6}-\dfrac{3}{6}+\dfrac{12}{6}=\dfrac{14}{6}=\dfrac{7}{3}\)

e) \(\dfrac{3}{5}+\dfrac{6}{11}+\dfrac{7}{13}+\dfrac{2}{5}+\dfrac{16}{11}+\dfrac{19}{13}=\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{6}{11}+\dfrac{16}{11}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)=1+2+2=5\)

g) \(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{29}{32}+\dfrac{1}{4}+\dfrac{3}{21}+\dfrac{13}{32}=\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{29}{32}+\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{13}{32}=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{29}{32}+\dfrac{13}{32}\right)=1+1+\dfrac{21}{16}=2+\dfrac{21}{16}=\dfrac{53}{16}\)

a,3/2+5/4+5/8 = 12/8 + 10/8 + 5/8 = 27/8

b,4/5-3/8+2/4 = 32/40 - 15/40 + 20/40 = 37/40

c,3+6/8-5/4= 24/8 + 6/8 - 10/8 = 20/8 = 5/2

d,5/6-1/2+2 = 5/6 - 3/6 + 12/6 = 14/6 = 7/3

e,3/5+6/11+7/13+2/5+16/11+19/13 = ( 3/5+ 2/5) + ( 6/11 + 16/11) + ( 7/13 + 19/13) = 1 + 2 + 2 = 5

g,75/100+18/21+29/32+1/4+3/21+13/32 = 3/4 + 6/7 + 29/32 + 1/4 + 1/7 + 13/32=  ( 3/4 + 1/4) + ( 29/32 + 13/32) + ( 6/7 + 1/7)= 1 + 21/16 + 1 = 53/16

- Phần a): phân tích thành các thừa số chung, rồi rút chúng ra ngoài dấu ngoặc, sau đó rút gọn.

- Phần b): phân tích một số thành tích các số, sau đó rút gọn các số giống nhau ở tử và mẫu.

mấy cái này ta chỉ cầm bấm máy tính thôi
\(\dfrac{7.25-49}{7.24+21}=\dfrac{2}{3}\)

\(\dfrac{2.\left(-13\right).9.10}{\left(-3\right).4.\left(-5\right).26}=\dfrac{-3}{2}\)

- Phần a): phân tích thành các thừa số chung, rồi rút chúng ra ngoài dấu ngoặc, sau đó rút gọn.

- Phần b): phân tích một số thành tích các số, sau đó rút gọn các số giống nhau ở tử và mẫu.

ẽ2d3z3

a, \(\frac{7.25-49}{7.24+21}\)

\(=\frac{7.25-7.7}{7.24+7.3}=\frac{7\left(25-7\right)}{7\left(24+3\right)}=\frac{18}{27}=\frac{2}{3}\)

b, \(\frac{2.\left(-13\right).9.10}{\left(-3\right).4.\left(-5\right).26}=\frac{2.\left(-13\right).\left(-3\right).\left(-3\right).\left(-5\right).\left(-2\right)}{\left(-3\right).2.2.\left(-5\right).\left(-13\right).\left(-2\right)}\)

\(=\frac{-3}{2}\)

DỄ LẮM !

a) \(\frac{7\cdot25-49}{7\cdot24+21}=\frac{7\cdot25-7\cdot7}{7\cdot24+7\cdot3}=\frac{7\left(25-7\right)}{7\left(24+3\right)}\)

=\(\frac{18}{27}=\frac{2}{3}\)

b) \(\frac{2\cdot\left(-13\right)\cdot9\cdot10}{\left(-3\right)\cdot4\cdot\left(-5\right)\cdot26}=\frac{-1\cdot2\cdot13\cdot3\cdot3\cdot5\cdot2}{1\cdot3\cdot2\cdot2\cdot5\cdot13\cdot2}=-\frac{3}{2}\)

Chúc bn học tốt !

\(a,\frac{2.25-49}{2.24+21}=\frac{2.25-7.7}{7.24+7.3}=\frac{7.\left(25-7\right)}{7.\left(24+3\right)}=\frac{2}{3}\)

\(b,\frac{2.\left(-13\right).9.10}{\left(-3\right).4.\left(-5\right).26}=\frac{2.\left(-1\right).13.3.3.5.2}{1.3.2.2.5.13.2}\frac{-3}{2}\)

`@` `\text {Ans}`

`\downarrow`

`1,`

`a)`

`-7/25 + (-8)/25`

`= (-7 - 8)/25`

`= -15/25`

`= -3/5`

`b)`

`6/13 + (-15)/39`

`= 18/39 + (-15)/39`

`= (18 - 15)/39`

`= 3/39`

`= 1/13`

`c)`

`5/7 + 4/(-14)`

`= 10/14 + (-4)/14`

`= (10 - 4)/14`

`= 6/14`

`= 3/7`

`d)`

`-8/18 + (-15)/27`

`= -4/9 + (-5)/9`

`= (-4-5)/9`

`= -9/9 = -1`

`2,`

`a)`

`3/5 + (-7)/4`

`= 12/20 + (-35)/20`

`= (12 - 35)/20`

`=-23/20`

`b)`

`(-2) + (-5)/8`

`= (-16)/8 + (-5)/8`

`= (-16 - 5)/8`

`= -21/8`

`c)`

`1/8 + (-5)/9`

`= 9/72 + (-40)/72`

`= (9-40)/72`

`= -31/72`

`d)`

`6/13 + (-14)/39`

`= 18/39 + (-14)/39`

`= (18 - 14)/39`

`= 4/39`

`e)`

`(-18)/24 + 15/21`

`= (-3)/4 + 5/7`

`= (-21)/28 + 20/28`

`= (-21 + 20)/28`

`= -1/28`

Cần chi tiết hum bẹn

a) = 76/35 ; 37/9

b) 143/40 ; 19/15

c) 2/3 ; 42/5

d) 21/4 ; 4/7 

a, 11/7 + 3/5

= \(\dfrac{11x5}{7x5}+\dfrac{3x7}{5x7}=\dfrac{55}{35}+\dfrac{21}{35}=\dfrac{76}{35}\)

4 + 1/9

= \(\dfrac{4}{1}+\dfrac{1}{9}=\dfrac{4x9}{1x9}+\dfrac{1x1}{9x1}=\dfrac{36}{9}+\dfrac{1}{9}=\dfrac{37}{9}\)

b, 21/5 - 5/8

= \(\dfrac{21x8}{5x8}-\dfrac{5x5}{8x5}=\dfrac{168}{40}-\dfrac{25}{40}=\dfrac{143}{40}\)

2 - 11/15

=\(\dfrac{2}{1}-\dfrac{11}{15}=\dfrac{30}{15}-\dfrac{11}{15}=\dfrac{19}{15}\)

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