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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
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
Bài 2 :
a, \(x=\dfrac{3}{5}-\dfrac{7}{8}=\dfrac{24-30}{40}=-\dfrac{6}{40}=-\dfrac{3}{20}\)
b, \(2x-1=-2\Leftrightarrow x=-\dfrac{1}{2}\)
a,\(\frac{7.9-14}{3-17}=\frac{63-14}{-14}=\frac{49}{-14}=\frac{7}{-2}\)
b,\(\frac{14}{9}\) c,\(0\)
k mình nha đồng thời kb hihi
\(\text{a)}25\%-\frac{3}{2}+0,5.\frac{12}{5}\)
\(=\frac{1}{4}-\frac{3}{2}+\frac{1}{2}.\frac{12}{5}\)
\(=-\frac{5}{8}+\frac{6}{5}\)
\(=-\frac{25}{40}+\frac{48}{40}\)
\(=\frac{23}{40}\)
\(b)0,25.\frac{7}{3}.30.\text{ }0,5.\frac{8}{45}\)
\(=\frac{1}{4}.\frac{7}{3}.30.\frac{1}{2}.\frac{8}{45}\)
\(=\frac{7}{12}.(30.\frac{8}{90})\)
\(=\frac{7}{12}.\frac{8}{3}\)
\(=\frac{14}{9}\)
\(c)\frac{9}{23}.\frac{5}{8}+\frac{9}{23}.\frac{3}{8}-\frac{9}{23}\)
\(=\frac{9}{23}.\left(\frac{5}{8}+\frac{3}{8}-1\right)\)
\(=\frac{9}{23}.0\)
\(=0\)
1/\(\left(-12\right)\cdot46-12\cdot54=\left(-12\right)\cdot46+\left(-12\right)\cdot54\)
\(=\left(-12\right)\cdot\left(46+54\right)=\left(-12\right)\cdot100=-1200\)
2/\(3784+23-3785-15=3785+22-3785-15\)
\(=22-15=7\)
3/\(\left(-8\right)\cdot25\cdot\left(-2\right)\cdot4\cdot\left(-5\right)\cdot125\)
\(=\left[\left(-8\right)\cdot125\right]\cdot\left[25\cdot4\right]\cdot\left[\left(-5\right)\cdot\left(-2\right)\right]\)
\(=\left(-1000\right)\cdot100\cdot10=-1000000\)
4/\(19\cdot25+9\cdot95+19\cdot30=19\cdot\left(25+30\right)+9\cdot95\)
\(=19\cdot55+9\cdot95=95\cdot11+9\cdot95=95\cdot\left(11+9\right)=20\cdot95=1900\)
5/\(\left(-50+19+143\right)-\left(-79+25+48\right)\)
\(=\left(-50\right)+19+143+79-25-48\)
\(=118\)
6/\(\left(-25\right)\cdot\left(75-45\right)-75\cdot\left(45-25\right)\)
\(=\left(-25\right)\cdot30+\left(-25\right)\cdot3\cdot20\)
\(=\left(-25\right)\cdot\left(30+60\right)=\left(-25\right)\cdot90=-2250\)
7/\(\left(-37-17\right)\cdot\left(-9\right)+35\left(-9-11\right)\)
\(=\left(-54\right)\cdot\left(-9\right)+35\cdot\left(-20\right)\)
\(=486+\left(-700\right)=-214\)
8/\(\left(187-23\right)-\left(20-180\right)\)
\(=187-23-20+180=324\)
9/\(512\cdot2-128\cdot\left(-512\right)\)
\(=512\cdot2+128\cdot512=512\cdot\left(2+128\right)\)
\(=512\cdot130=66560\)
10/\(17\cdot\left(-25\right)+25\cdot21\)
\(=17\cdot\left(-25\right)-\left(-25\right)\cdot21=\left(-25\right)\cdot\left(17-21\right)\)
\(=\left(-25\right)\cdot\left(-4\right)=100\)
Chúc bạn học tốt.