a)[(-7)+(-93)]+[(-125)+(-25)

=-100+-150

=-250

b)2012+(-1000)+(-12)+(-500)

=[2012+(-12)]+[(-1000)+(-500)]

=2000+-1500

=-500

c)(-12).7+(-8).7+4.(-25)+(-6).(-25)

=7[(-12)+(-8)]+-25[4+-6]

=7.(-20)+-25.-2

=-140+50

=-90

a) (-7) + (-125) + (-93) + (-25)

= -7 - 125 - 93 - 25

= (-7 - 93) - (125 + 25)

= -100 + (-150)

= -250

b) 2012 + (-1000) + (-12) + (-500)

= (2012 - 12) - (1000 + 500)

= 2000 - 1500

= 500

c) (-12).7 + (-8).7 + 4.(-25) + (-6) . (-25)

= (-12 + (-8) . 7 + (4 + (-6) . (-25)

= -20 .7 + (-2) . (-25)

= -2 . 10 . 7 + (-2)  . 25

= -2 . 70 + (-2) . 25

= -2 . (70 + 25)

= -2 . 95

= -190

\(\dfrac{2}{15}\times\dfrac{1}{8}\times\dfrac{15}{12}=1\times\dfrac{1}{8}\times\dfrac{1}{6}=\dfrac{1}{48}\)

=(2/15x15/12)x1/8

= 1/6x 1/8

= 1/48

( nếu có sai thì thui nha)

Bài 10:

a: x-5=-1

=>x=-1+5

=>x=4

b: x+30=-4

=>x=-4-30

=>x=-34

c: x-(-24)=3

=>x+24=3

=>x=3-24

=>x=-21

d: 22-(-x)=12

=>22+x=12

=>x=12-22

=>x=-10

e: (x+5)+(x-9)=x+2

=>x+5+x-9=x+2

=>2x-4=x+2

=>2x-x=4+2

=>x=6

f: (27-x)+(15+x)=x-24

=>x-24=27-x+15+x=42

=>x=42+24

=>x=66

Bài 9:

a: 15-(4-x)=6

=>4-x=15-6=9

=>x=4-9=-5

b: -30+(25-x)=-1

=>-30+25-x=-1

=>-5-x=-1

=>x+5=1

=>x=1-5

=>x=-4

c: x-(12-25)=-8

=>x-(-13)=-8

=>x+13=-8

=>x=-8-13

=>x=-21

d: (x-29)-(17-38)=-9

=>x-29-(-21)=-9

=>x-29+21=-9

=>x-8=-9

=>x=-9+8

=>x=-1

Bài 8:

a: (17-229)+(17-25+229)

=17-229+17-25+229

=34-25

=9

b: (125-679+145)-(125-679)

=125-679+145-125+679

=145

\(a)9.4.25.8.125\)

\(=9.\left(4.25\right).\left(8.125\right)\)

\(=9.100.1000\)

\(=900.1000\)

\(=900000\)

\(a,9.4.25.8.125=9.\left(4.25\right).\left(8.125\right)=9.100.1000=900000\)

\(b,25.5.27.2\)(câu này hình như thiếu đề, ko tính nhanh đc)

\(c,37.7+80.3+43.7\)\(=7.\left(37+43\right)+80.3\)\(=7.80+3.80=80\left(7+3\right)=80.10=800\)

\(d,113.38+113.62+87.62+87.38\)\(=113\left(38+62\right)+87\left(62+38\right)\)

\(=113.100+87.100=100.\left(113+87\right)=100.200=20000\)

Viết gọn lũy thừa:

\(a,x.x.y.y.x.y.x=\left(x.x.x.x\right).\left(y.y.y\right)=x^4.y^4\)

\(b,7^5:343=7^5:7^3=7^{5-3}=7^2\)

\(c,A^{12}:A^{18}=A^{12-18}=A^{-6}\)

\(d,x^7.x^4.x=x^{7+4+1}=x^{12}\)

a,\(\frac{37.13-13}{24+37.12}=\frac{36.13}{39.12}=1\)

b,125.7.16.25.4=(125.16).(25.4).7=2000.100.7=1400000

c,8.9.14+6.17.12+19.4.18=2^3.3^2.2.7+2.3.17.2^2.3+19.2^2.3^2.2=2^3.3^2.(2.7+17+19)=72.50=3600

2/5

2/5