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a/ 7*25-49/7*24+21
=( 7*25 ) - ( 49/7 ) * ( 24+21)
= 175 - 7 * 45
= 175 - ( 7*45 )
=175 - 315
= -140
mk k bít đúng k
\(a,\frac{2}{3}>\frac{1}{4}\)
\(b,\frac{7}{10}< \frac{7}{8}\)
\(c,\frac{6}{7}>\frac{3}{5}\)
\(d,\frac{14}{21}< \frac{60}{72}\)
\(e,\frac{16}{9}< \frac{24}{13}\)
\(g,\frac{27}{82}< \frac{26}{75}\)
a 2/3 > 1/4
b 7/10 < 7/8
c6/7 > 3/5
d14/21 < 60/72
e16/9 < 24/13
g27/82<26/75
1. \(\frac{9}{30}=\frac{3}{10};\frac{98}{80}=\frac{49}{40};\frac{15}{1000}=\frac{3}{200}\)
Vì \(200⋮10;200⋮40\)
=> BCNN(10; 40; 200) = 200
200 : 10 = 20
200 : 40 = 5
=> \(\frac{3}{10}=\frac{3\cdot20}{10\cdot20}=\frac{60}{200}\), \(\frac{49}{40}=\frac{49\cdot5}{40\cdot5}=\frac{245}{200}\)
a; \(\dfrac{9}{27}\) + \(\dfrac{7}{-49}\)
= \(\dfrac{1}{3}\) - \(\dfrac{1}{7}\)
= \(\dfrac{7}{21}\) - \(\dfrac{3}{21}\)
= \(\dfrac{4}{21}\)
b; - \(\dfrac{12}{10}\) + \(\dfrac{-25}{30}\)
= - \(\dfrac{6}{5}\) - \(\dfrac{5}{6}\)
= -\(\dfrac{36}{30}\) - \(\dfrac{25}{30}\)
= \(\dfrac{-61}{30}\)
c; \(\dfrac{-20}{35}\) + \(\dfrac{-16}{-24}\)
= - \(\dfrac{4}{7}\) + \(\dfrac{2}{3}\)
= - \(\dfrac{12}{21}\) + \(\dfrac{14}{21}\)
= \(\dfrac{2}{21}\)
d; - \(\dfrac{21}{77}\) + \(\dfrac{10}{-35}\)
= - \(\dfrac{3}{11}\) - \(\dfrac{2}{7}\)
= - \(\dfrac{21}{77}\) - \(\dfrac{22}{77}\)
= - \(\dfrac{43}{77}\)
Câu a:
- |- 5 + 3 - 7| - |- 5 + 7|
= -|- 2 - 7| - |2|
= - |-9| - 2
= - 9 - 2
= -11
Câu b:
24 - (72 - 13 + 24) - (72 - 13)
= 24 - 72 + 13 - 24 - 72 + 13
= (24 - 24) - (72 + 72) + (13 + 13)
= 0 - 144 + 26
= - 118
Câu c:
|4 - 9 - 5| - (4 - 9 - 5) - 15 + 9
=|- 5 - 5| - (- 5 - 5) - 15 + 9
= |-10| - (-10) - 15 + 9
= 10 + 10 - 15 + 9
= 20 - 15+ 9
= 5 +9
= 14
Câu d:
- 20 - (25 - 11 + 8) +(25 - 8 + 20)
= - 20 - 25 + 11 - 8 + 25 - 8 + 20
= (-20 + 20) + (25 - 25) + (11 - 8- 8)
= 0 + 0+ 3 - 8
= -5
1,
a,-3/5
b,-1/2
c,19/39
d,1/4
e,-39/40
f,-59/56
2,
a,=
b,<
c,>
d,<
k cho mình nha