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`a)3/5+(-4/9)`
`=3/5-4/9`
`=27/45-20/45`
`=7/45`
`b)3/5+2/5 . 15/8`
`=3/5 + 30/40`
`=3/5+3/4`
`=12/20+15/20`
`=27/20`
`c)7/2 . 8/13 + 8/13 . (-5/2)`
`=8/13 . (7/2 +(-5)/2)`
`=8/13 . 1`
`=8/13`
`d)-5/17 . (-9/23)+9/23 . (-22/17) + 11 9/23`
`=-5/17 . (-9/23) + 9/23 . (-1) . 22/17 + 11 + 9/23`
`=-5/17 . (-9/23) + (-9/23) . 22/17+11+9/23`
`= -9/23 ( -5/17 + 22/17)+11+9/23`
`= - 9/23 . 1+11+9/23`
`=-9/23+11+9/23`
`=(-9/23+9/23)+11`
`=0+11`
`=11`
a: =27/45-20/45=7/45
b: =3/5+30/40
=3/5+3/4
=12/20+15/20
=27/20
c: =8/13(7/2-5/2+1)=8/13*2=16/13
d: =9/23*5/17-9/23*22/17+11+9/23
=-9/23+11+9/23
=11
Bài 2 :
a, \(x=\dfrac{3}{5}-\dfrac{7}{8}=\dfrac{24-30}{40}=-\dfrac{6}{40}=-\dfrac{3}{20}\)
b, \(2x-1=-2\Leftrightarrow x=-\dfrac{1}{2}\)
\(-\frac{3}{5}.\frac{11}{7}+\frac{3}{-5}.\frac{4}{7}+\frac{23}{7}\)
\(=\frac{-3}{5}\left(\frac{11}{7}+\frac{4}{7}\right)+\frac{23}{7}\)
\(=\frac{-3}{5}.\frac{15}{7}+\frac{23}{7}\)
\(=\frac{-9}{7}+\frac{23}{7}=2\)
\(=\dfrac{9}{23}\left(\dfrac{5}{17}-\dfrac{22}{17}\right)+11+\dfrac{9}{23}=11\)
a)=(4.25).37
=100.37
=3700
b)=(132+868)+(763+237)+29
=1000+1000+29
=2029
c)=72+[131-1.20]
=49+[131-20]
=49+111
=160
a) \(\dfrac{7}{30}+\dfrac{\left(-12\right)}{37}+\dfrac{23}{30}+\dfrac{\left(-25\right)}{37}=\left(\dfrac{7}{30}+\dfrac{23}{30}\right)+\left(\dfrac{-12}{37}+\dfrac{-25}{37}\right)=1+\left(-1\right)=0\)
b) \(\dfrac{5}{7}\cdot\dfrac{5}{11}+\dfrac{5}{7}\cdot\dfrac{2}{11}-\dfrac{5}{7}\cdot\dfrac{14}{11}=\dfrac{5}{7}\cdot\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)=\dfrac{5}{7}\cdot\left(-\dfrac{7}{11}\right)=-\dfrac{5}{11}\)
c) \(\dfrac{\left(-5\right)}{7}\cdot\dfrac{3}{13}-\dfrac{5}{7}\cdot\dfrac{10}{13}+1\dfrac{5}{7}=\dfrac{5}{7}\cdot\dfrac{-3}{13}-\dfrac{5}{7}\cdot\dfrac{10}{13}+\dfrac{12}{7}=\dfrac{5}{7}\cdot\left(\dfrac{-3}{13}-\dfrac{10}{13}\right)+\dfrac{12}{7}=\dfrac{5}{7}\cdot\left(-1\right)+\dfrac{12}{7}=\left(-\dfrac{5}{7}\right)+\dfrac{12}{7}=\dfrac{7}{7}=1\)
a: \(\left(-17\right)+5+\left(-8\right)+17\)
\(=\left(-17+17\right)+\left(5-8\right)\)
=0-3
=-3
b: \(\left(-9\right)+\left(-11\right)+21+\left(-1\right)\)
\(=\left(-9-1\right)+\left(21-11\right)\)
=10-10
=0
c: \(15+23+\left(-25\right)+\left(-23\right)\)
\(=\left(15-25\right)+\left(23-23\right)\)
=-10+0
=-10
d: \(\left(-3\right)+\left(-350\right)+\left(-7\right)+350\)
\(=\left(-3-7\right)+\left(-350+350\right)\)
=-10+0
=-10
e: \(\left(-3\right)+\left(-250\right)+\left(-7\right)+250\)
\(=\left(-3-7\right)+\left(-250+250\right)\)
=-10+0
=-10
f: \(\left(-4\right)+\left(-440\right)+\left(-6\right)+440\)
\(=\left(-4-6\right)+\left(-440+440\right)\)
=-10+0
=-10
g: \(483+\left(-56\right)+263+\left(-64\right)\)
\(=\left(483+263\right)+\left(-56-64\right)\)
\(=746-110=636\)
h: \(215+43+\left(-215\right)+\left(-25\right)\)
\(=\left(215-215\right)+\left(43-25\right)\)
=0+18
=18
a. (-17) + 5 + (-8) + 17
= [5 + (-8)] + [(-17) + 17]
= -3
b. (-9) + (-11) + 21 + (-1)
= [(-9) + (-1)] + [21 + (-11)]
= -10 + 10
= 0
c. 15 + 23 + (-25) + (-23)
= [15 + (-25)] + (23 - 23)
= -10
d. (-3) + (-350) + (-7) + 350
= [(-3) + (-7)] + [(-350) + 350]
= -10
e. (-3) + (-250) + (-7) + 250
= [(-3) + (-7)] + [(-250) + 250]
= -10
f. (-4) + (-440) + (-6) + 440
= [(-4) + (-6)] + [(-440) + 440]
= -10
g. 483 + (-56) + 263 + (-64)
= (483 + 263) + [(-56) + (-64)]
= 746 + (-120)
= 626
h. 215 + 43 + (-215) + (-25)
= [215 + (-215)] + [43 + (-25)]
= 18