a, A = 27.36+73.99+27.14 - 49.73

= 27(36+14)+73(99 - 49)

= 27.50 + 73.50 = 50(27+73) = 50.100 = 5000

b, B =  4 5 . 10 . 5 6 + 25 5 . 2 8 : 2 8 . 5 4 + 5 7 . 2 5

Ta có: 4 5 = 2 2 5 = 2 2 . 5 = 2 10 ; 25 5 = 5 2 5 = 5 2 . 5 = 5 10

=>  4 5 . 10 . 5 6 + 25 5 . 2 8 = 2 10 . 2 . 5 . 5 6 + 5 10 . 2 8 =  2 11 . 5 7 + 5 10 . 2 8 =  2 8 . 2 3 . 5 7 + 5 7 . 5 3 . 2 8 =  2 8 . 5 7 . 2 3 + 5 3

Ta lại có:  2 8 . 5 4 + 5 7 . 2 5 = 2 5 . 2 3 . 5 4 + 5 4 . 5 3 . 2 5 =  2 5 . 5 4 . 2 3 + 5 3

Suy ra B =  2 8 . 5 7 . 2 3 + 5 3 :[ 2 5 . 5 4 . 2 3 + 5 3 ] =  2 8 . 5 7 : 2 5 . 5 4

=  2 8 : 2 5 . 5 7 : 5 4 =  2 3 . 5 3 = 2 . 5 3 = 10 3 = 1000

a, A = 27.36+73.99+27.14 - 49.73

= 27(36+14)+73(99 - 49)

= 27.50 + 73.50 = 50(27+73) = 50.100 = 5000

b, B =  4 5 . 10 . 5 6 + 25 5 . 2 8 : 2 8 . 5 4 + 5 7 . 2 5

Ta có: 4 5 = 2 2 5 = 2 2 . 5 = 2 10 ; 25 5 = 5 2 5 = 5 2 . 5 = 5 10

=>  4 5 . 10 . 5 6 + 25 5 . 2 8 = 2 10 . 2 . 5 . 5 6 + 5 10 . 2 8 =  2 11 . 5 7 + 5 10 . 2 8 =  2 8 . 2 3 . 5 7 + 5 7 . 5 3 . 2 8 =  2 8 . 5 7 . 2 3 + 5 3

Ta lại có:  2 8 . 5 4 + 5 7 . 2 5 = 2 5 . 2 3 . 5 4 + 5 4 . 5 3 . 2 5 =  2 5 . 5 4 . 2 3 + 5 3

Suy ra B =  2 8 . 5 7 . 2 3 + 5 3 :[ 2 5 . 5 4 . 2 3 + 5 3 ] =  2 8 . 5 7 : 2 5 . 5 4

=  2 8 : 2 5 . 5 7 : 5 4 =  2 3 . 5 3 = 2 . 5 3 = 10 3 = 1000

A = 27.36+73.99+27.14-49.73

A=27(36+14)+73(99-49)

A=27.50+79.50

A=50(27+79)

A=50.100=5000

27 . 36 + 73 . 99 + 27 . 14 - 49 . 73 = 27 . ( 36 + 14 ) + 73 . ( 99 - 49 )

                                                    = 27 . 50 + 73 . 50

                                                    = 50 . ( 73 + 27 )

                                                    = 50 . 100

                                                    = 5000

CHÚC BẠN HOK GIỎI :))

 bằng  -3/14

Nhớ k cho mình nha :3

cho mjk hoi ca cach lam ban a

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\(\frac{1}{3}.\frac{5}{7}-\frac{7}{27}.\frac{36}{14}\)

\(=\frac{1}{3}.\frac{5}{7}-\frac{7}{27}.\frac{18}{7}\)

\(=\frac{1.5}{3.7}-\frac{7.18}{27.7}\)

\(=\frac{5}{21}-\frac{2}{3}\)

\(=\frac{5}{21}-\frac{14}{21}=\frac{-9}{21}=\frac{-3}{7}\)

Chúc bn học tốt

a) \(A=27\cdot36+73\cdot99+27\cdot14-49\cdot73\)

\(A=27\cdot\left(36+14\right)+73\cdot\left(99-49\right)\)

\(A=27\cdot50+73\cdot50\)

\(A=50\cdot\left(27+73\right)\)

\(A=50\cdot100\)

\(A=5000\)

b) \(B=\left(4^5\cdot10\cdot5^6+25^5\cdot2^8\right):\left(2^8\cdot5^4+5^7\cdot2^5\right)\)

\(B=\dfrac{\left(2^2\right)^5\cdot2\cdot5\cdot5^6+\left(5^2\right)^5\cdot2^8}{2^8\cdot5^4+5^7\cdot2^5}\)

\(B=\dfrac{2^{11}\cdot5^7+5^{10}\cdot2^8}{2^8\cdot5^4+5^7\cdot2^5}\)

\(B-\dfrac{2^8\cdot5^7\cdot\left(2^3\cdot1+5^3\cdot1\right)}{2^5\cdot5^4\cdot\left(2^3\cdot1+5^3\cdot1\right)}\)

\(B=\dfrac{2^8\cdot5^7}{2^5\cdot5^4}\)

\(B=2^3\cdot5^3\)

\(B=10^3\)

\(B=1000\)

a: \(=\dfrac{1}{2}\cdot\dfrac{2\cdot21+3\cdot27-5\cdot7}{189}\)

\(=\dfrac{1}{2}\cdot\dfrac{88}{189}=\dfrac{44}{189}\)

b: \(=\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{3}{4}+\dfrac{4}{5}=\dfrac{1}{2}+\dfrac{4}{5}=\dfrac{13}{10}\)

c: \(=\dfrac{5}{21}-\dfrac{7}{14}\cdot\dfrac{36}{27}=\dfrac{5}{21}-\dfrac{1}{2}\cdot\dfrac{4}{3}=\dfrac{5}{21}-\dfrac{2}{3}=\dfrac{5-14}{21}=\dfrac{-9}{21}=\dfrac{-3}{7}\)

\(\frac{1}{2}\cdot\left(\frac{2}{9}+\frac{3}{7}-\frac{5}{27}\right)=\frac{1}{2}\cdot\left(\frac{6}{27}-\frac{5}{27}+\frac{3}{7}\right)=\frac{1}{2}\cdot\frac{3}{7}+\frac{1}{2}\cdot\frac{1}{27}=\frac{3}{14}+\frac{1}{54}=\frac{44}{189}\)

\(\frac{1}{2}+\frac{3}{4}-\left(\frac{3}{4}-\frac{4}{5}\right)=\frac{1}{2}+\frac{3}{4}-\frac{3}{4}+\frac{4}{5}=\frac{1}{2}+\frac{4}{5}=\frac{13}{10}\)

\(\frac{1}{3}\cdot\frac{5}{7}-\frac{7}{27}\cdot\frac{36}{14}=\frac{1}{3}\cdot\frac{5}{7}-\frac{7}{27}\cdot\frac{18}{7}=\frac{1}{3}\cdot\frac{5}{7}-\frac{6}{7}=\frac{5}{21}-\frac{14}{21}=\frac{-3}{7}\)

a/ -388.22

b/  -900

1/ 1/7=5/35

1/5=7/35

mak 1/7<x/35<1/5<=>5/35<x/35<7/35

=>x=6

a) -73/100= - 0,73

=14 . -27+(-0,73)

=14.(-27,73)

=-388,22

a) \(227+50+23=\left(227+23\right)+50=250+50=300\)

b) \(135+360+65+40=\left(135+65\right)+\left(360+40\right)=200+400=600\)

c) \(1+2+3+4+5+...+97+98+99+100\)

\(=\left(100+1\right)+\left(99+2\right)+...+\left(50+51\right)\)

\(=101+101+101+...+101\)

\(=101\cdot50\)

\(\Leftrightarrow5050\)

d) \(115\cdot13-13\cdot15=13\cdot\left(115-15\right)=13\cdot100=1300\)

e) \(50-49+48-47+...+4-3+2-1\)

\(=\left(50-49\right)+\left(48-47\right)+...+\left(2-1\right)\)

\(=1+1+1+1+..+1\)

\(=1\cdot25\)

\(=25\)

f) \(30\cdot40\cdot50\cdot60=10\cdot3+10\cdot4+10\cdot5+10\cdot6\)

\(=10\cdot10\cdot10\cdot10\cdot3\cdot4\cdot5\cdot6\)

\(=10000\cdot360\)

\(=3600000\)

g) \(27\cdot36+27\cdot64=27\cdot\left(36+64\right)=27\cdot100=2700\)

h) \(5\cdot2^2-18:3=5\cdot4-18:3=20-6=14\)

i) \(13\cdot17-256:16+14:7-2021^0\)

\(=13\cdot17-4^4:4^2+2-1\)

\(=13\cdot17-16+2-1\)

\(=13\cdot17-17\)

\(=17\cdot\left(13-1\right)\)

\(=204\)

j) \(7^2-36:3=49-12=37\)