\(a)\)

\(\left(-31\right)+\left(50-19\right)-\left(150-31\right)\)

\(=\left(-31\right)+50-19-150+31\)

\(=\left(-150\right)-19\)

\(=-169\)

\(b)\)

\(25.\left(45-17\right)-45.\left(25-17\right)\)

\(=25.45-25.17-45.25+45.17\)

\(=0\)

\(c)\)

\(\frac{-1}{12}+\frac{4}{3}=\frac{5}{4}\)

\(d)\)

\(3+\frac{-5}{20}+\frac{30}{75}+\frac{-7}{4}\)

\(=\left(\frac{3}{5}+\frac{30}{75}\right)-\left(\frac{5}{20}+\frac{7}{4}\right)\)

\(=1-2\)

\(=-1\)

a) (-31)+(50-19)-(150-31)

= (-31)+50+(-19)-150+(-31)
= (-31)+50-150+(-19)-(-31)
= (-31)+(-100)+12
= -119
b) 25(45-17)-45(25-17)
= 25.45-25.17-45.25-45.17
= 25(45-45)-25(17-17)
= 0
c) -1/12 + 4/3
= -1/12 + 16/12
= 15/12
= 5/4
d) 3/5+(-5)/20+30/75+(-7)/4
= 45/75+30/75+(-5)/20+(-35)/20
= 1+(-2)
= -1

a: \(-177-\left\lbrack89+\left(-177\right)+75\right\rbrack-\left(-25\right)\)

=-177-[89-177+75]+25

=-177-89+177-75+25

=-89-50

=-139

b: \(2\cdot\left\lbrack16+\left(-12\right)-5\right\rbrack+\left(-32\right)-\left(-10\right)\)

\(=2\cdot\left\lbrack16-17\right\rbrack-32+10\)

=2*(-1)-32+10

=-34+10

=-24

c: \(56\cdot53-\left\lbrack57+\left(-75\right)-\left(-9\right)\cdot2\right\rbrack\)

=2968-[57-75+18]

=2968

d: \(16\cdot\left(-45\right)+16\cdot34-\left(-16\right)\cdot\left(-89\right)\)

\(=16\left(-45+34\right)-16\cdot89\)

\(=16\left(-11-89\right)=16\cdot\left(-100\right)=-1600\)

e: \(77\cdot18-\left(-77\right)\cdot60+\left(-77\right)\cdot\left(-22\right)\)

\(=77\cdot18+77\cdot60+77\cdot22\)

\(=77\left(18+60+22\right)=77\cdot100=7700\)

A = 36/5

#)Giải :

\(\frac{1}{15}+\frac{4}{30}+\frac{9}{45}+\frac{16}{60}+...+\frac{81}{135}=\frac{1}{15}+\frac{2}{15}+\frac{3}{15}+...+\frac{9}{15}=\frac{45}{15}=3\)

Dễ ẹc ak :v rút gọn là ra

=(\(\frac{1}{15}\)+\(\frac{4}{30}\)+\(\frac{16}{60}\)+\(\frac{64}{120}\))+(\(\frac{9}{45}\)+\(\frac{36}{90}\))+(\(\frac{25}{75}\)+\(\frac{81}{135}\))

=(\(\frac{8}{120}\)+\(\frac{16}{120}\)+\(\frac{32}{120}\)+\(\frac{64}{120}\))+(\(\frac{18}{90}\)+\(\frac{36}{90}\))+\(\frac{14}{15}\).

=1+\(\frac{3}{5}\)+\(\frac{14}{15}\).

=\(\frac{8}{5}\)+\(\frac{14}{15}\).

=\(\frac{15}{38}\)

a) (14 + 38 + 66) - (10 + 4 - 16)

= 14 + 38 + 66 - 10 - 4 + 16

= (14 - 4) + (66 + 38 + 16) - 10

= 10 + 120 - 10

= 120

b) (70 + 20 - 60) - (-30 - 80 + 120)

= 70 + 20 - 60 + 30 + 80 - 120

= (70 + 30) + (20 + 80) - (120 + 60)

= 100 + 100 - 180

= 200 - 180

= 20

a, (14 + 38 + 66) - (10 + 4 - 16)

   = 14 + 38 + 66 - 10 - 4 + 16

= (14 - 4 - 10) + (38 + 66 + 16)

= 0 + 120

= 120 

Bài 1:BC Của 12 Và -30 Là { 60; -60; 120; -120; 180; -180}

Bài 2: ƯC Của -60; 45 và -105 Là { 1; 3; 5; 15}

mấy bạn nhớ trình bày chi tiết ra giúp mik nha

\(M=\frac{1}{10}+\frac{4}{20}+\frac{9}{30}+\frac{16}{40}+...+\frac{81}{90}\)

\(M=\frac{1}{10}+\frac{2}{10}+\frac{3}{10}+\frac{4}{10}+...+\frac{9}{10}\)

\(M=\frac{\left(9+1\right)\cdot\left(9-1+1\right):2}{10}\)

\(M=\frac{10\cdot9:2}{10}=4,5\)

tớ làm giống bạn kia

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