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a.
= -30-15+21-30-15-9
= (-30 - 30)+(-15-15)+(21-9)
= -60 -30 + 12
= -78
b.
= (6-18)+(-5+4)+(-20+21)
= 12 + (-1) + 1
=12
c.
= 27.(19+31)
=27. 50
= 1350
d.
= (-25).(64+36)
= -25 . 100
= -2500
e. 18.36 + 72.15
= 18.36 + 4.18.15
=18.( 36 + 60)
= 18.96
= 1728
Câu b bạn đang nhầm một chút, bạn sửa lại nhé.
`@` `\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`
ó ai giúp mk ko , ai giúp mk nhanh và đúng mk sẽ k cho người đó nhé , ( nhanh chứ ko mk đâng cần)
1.
a, \(\left(15+37\right)+\left(52-37-17\right)\)
\(=15+37+52-37-17\)
\(=50\)
b, \(\left(38-42+14\right)-\left(25-27-15\right)\)
\(=38-42+14-25+27+15\)
\(=27\)
c, \(-\left(21-32\right)-\left(-12+32\right)\)
\(=-21+32+12-32\)
\(=-9\)
d, \(-\left(12+21-23\right)-\left(-23-21+10\right)\)
\(=-12-21+23+23+21-10\)
\(=24\)
e, \(\left(57-725\right)-\left(605-53\right)\)
\(=57-725-605+53\)
\(=-1220\)
f, \(\left(55+45+15\right)-\left(15-55+45\right)\)
\(=55+45+15-15+55-45\)
\(=110\)
2.
c, \(25\left(-47\right)\left(-4\right)\)
\(=-100\left(-47\right)=4700\)
d, \(8\left(125-30000\right)\)
\(=8.125-8.30000\)
\(=1000.240000\)
\(=240000000\)
e, \(512\left(2-128\right)-128\left(-512\right)\)
\(=512\left(2-128\right)+128.512\)
\(=512\left(2-128+128\right)\)
\(=1024\)
3.
4 B(-5) trog đó cs cả số âm là: 10; -20; 35; -40
tất cả các Ư(15) là: \(\pm1;\pm3;\pm5;\pm15\)
LƯU Ý: đề hơi dài, cs sai sót j mong e bỏ qua mà k cho cj nha
a: \(=\dfrac{5}{6}\cdot\dfrac{-12}{7}=\dfrac{-10}{7}\)
b: \(=\dfrac{7}{8}\cdot\dfrac{8}{14}=\dfrac{7}{14}=\dfrac{1}{2}\)
c: \(=\dfrac{4}{5}\cdot\dfrac{-15}{8}=\dfrac{-3}{2}\)
d: \(=\dfrac{15}{16}\cdot\dfrac{8}{25}=\dfrac{15}{25}\cdot\dfrac{1}{2}=\dfrac{3}{5}\cdot\dfrac{1}{2}=\dfrac{3}{10}\)
đ: \(=\dfrac{2}{3}-\dfrac{70}{175}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{10-6}{15}=\dfrac{4}{15}\)
Bài 1:
a; \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{7}{21}\) + (- \(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)
= \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{1}{3}\) -\(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\) - \(\dfrac{5}{8}\)
= (\(\dfrac{5}{18}\) - \(\dfrac{10}{36}\)) + (\(\dfrac{8}{19}\) + \(\dfrac{11}{19}\)) - (\(\dfrac{1}{3}\) - \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)
= (\(\dfrac{5}{18}\) - \(\dfrac{5}{18}\)) + \(\dfrac{19}{19}\) - 0 - \(\dfrac{5}{8}\)
= 0 + 1 - \(\dfrac{5}{8}\)
= \(\dfrac{3}{8}\)
b; \(\dfrac{1}{13}\) + (\(\dfrac{-5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\)) - (\(\dfrac{12}{17}\) - \(\dfrac{5}{18}\) + \(\dfrac{7}{5}\))
= \(\dfrac{1}{13}\) - \(\dfrac{5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{12}{17}\) + \(\dfrac{5}{18}\) - \(\dfrac{7}{5}\)
= (\(\dfrac{1}{13}\) - \(\dfrac{1}{13}\)) + (\(\dfrac{12}{17}\) - \(\dfrac{12}{17}\)) + (-\(\dfrac{5}{18}\) + \(\dfrac{5}{18}\)) - \(\dfrac{7}{5}\)
= 0 + 0 + 0 - \(\dfrac{7}{5}\)
= - \(\dfrac{7}{5}\)
Bài 1 c;
\(\dfrac{15}{14}\) - (\(\dfrac{17}{23}\) - \(\dfrac{80}{87}\) + \(\dfrac{5}{4}\)) + (\(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\))
= \(\dfrac{15}{14}\) - \(\dfrac{17}{23}\) + \(\dfrac{80}{87}\) - \(\dfrac{5}{4}\) + \(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\)
= (\(\dfrac{15}{14}-\dfrac{15}{14}\)) + (\(-\dfrac{17}{23}+\dfrac{17}{23}\)) - (\(\dfrac{5}{4}\) - \(\dfrac{1}{4}\)) + \(\dfrac{80}{87}\)
= 0 + 0 - 1 + \(\dfrac{80}{87}\)
= - \(\dfrac{7}{87}\)
a)=-50
b)=-33
c)=13
d)=46
e)=-33
f)=-54
g)=29
h)=-11
i)=-120
k)=-196
l)=-108
m)=100
a)=-50
b)=-33
c)=13
d)=46
e)=-33
f)=-54
g)=29
h)=-11
i)=-120
k)=-196
l)=-108
m)=100
a,=128+62+25
=190+25
=215
b,=-75+[-5]+[-18]
=-80+[-18]
=-98
c,=21+14+15
=35+15
=50
d,[-12]+[-15]-25
=-27-25
=-52
e,=28+[-25]-10
=3-10=-7
f,=-1+2+[-30]+4+[-5]
=1+[-30]+{4+[-5]}
=-29+[-1]
=-30
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