a. Đ

b. S

c. Đ

d. S

A.35 x 34 + 35 x 38 + 65 x 75 + 65 x 45

Câu này không tính hợp lí được

B. 12x 53 + 53 x 172 - 53 x 84

= 53 x (12 + 172 - 84)

= 53 x 100

= 5300

C. 36 x 28 + 36 x 82 + 64 x 69 + 64 x 41

= 36 x (28+82) + 64 x (69+41)

= 36 x 110 + 64 x 110

= (36+64) x 110

= 100 x 110

= 11 000

D. A = 1+2+3+...+100

= (1+ 100) x 50

= 101 x 50

= 5050

E. B =17+19+...+101+103

= (103 +17) x [(103 - 17):2 + 1]

= 120 x 44

=5280

G. D= 3x (12+13+14+15) + 3x(8+7+6+5)

= 3 x (5+6+7+8+12+13+14+15)

= 3 x (20 x 4)

= 3 x 80

=240

a) 10320

b) 5300

c) 11000

d) 5050

e) 2460

g)  240

\(\frac{31}{53}.\frac{17}{28}+\frac{31}{28}.\frac{11}{53}\)

\(=\frac{31}{53}.\frac{17}{28}+\frac{11}{28}.\frac{31}{53}\)

\(=\frac{31}{53}.\left(\frac{17}{28}+\frac{11}{28}\right)\)

\(=\frac{31}{53}.1\)

\(=\frac{31}{53}\)

\(\frac{31}{53}\times\frac{17}{28}+\frac{31}{28}\times\frac{11}{53}\)

\(=\frac{31}{53}\times\frac{17}{28}+\frac{31}{53}\times\frac{11}{28}\)

\(=\frac{31}{53}\times\left(\frac{17}{28}+\frac{11}{28}\right)\)

\(=\frac{31}{53}\times1\)

\(=\frac{31}{53}\)

\(\frac{31}{53}.\frac{17}{28}+\frac{31}{28}.\frac{11}{53}=\frac{31}{53}.\frac{17}{28}+\frac{31}{53}.\frac{11}{28}\)

 \(=\frac{31}{53}.\left(\frac{17}{28}+\frac{11}{28}\right)=\frac{31}{53}.1=\frac{31}{53}.\)

a, 39*49-39*17    

= 39 (49 - 17)

= 39 * 32

= 1248

b,12*53+53*172-53*84

= 53 (12 + 172 -84)

= 53 * 100

= 5300

c,17+18+19+99  

= 17 + 17 +1 + 17 +2 + 99

= 3 * 17 + (1+ 99) + 2

= 151 +2

= 153

d, 23+25+49

= 48 + 49

= 97

e,46-45+44-43

= (46 + 44) + (-45 -43)

= 88 + (-88)

= 0

\(\frac{47}{53}\div\frac{17}{52}-\frac{47}{53}\times\frac{35}{17}\)

\(=\frac{47}{53}\times\frac{52}{17}-\frac{47}{53}\times\frac{35}{17}\)

\(=\frac{47}{53}\times(\frac{52}{17}-\frac{35}{17)}\)

\(=\frac{47}{53}\times\frac{17}{17}=\frac{47}{53}\times1=\frac{47}{53}\)

a) \(\dfrac{25}{37}\times\dfrac{18}{29}+\dfrac{18}{29}\times\dfrac{12}{37}\)

\(=\dfrac{18}{29}\times\left(\dfrac{25}{37}+\dfrac{12}{37}\right)\)

\(=\dfrac{18}{29}\times\dfrac{37}{37}\)

\(=\dfrac{18}{29}\times1\)

\(=\dfrac{18}{29}\)

b) \(\dfrac{31}{85}\times\dfrac{11}{19}+\dfrac{31}{85}\times\dfrac{12}{19}-\dfrac{42}{19}\times\dfrac{31}{85}\)

\(=\dfrac{31}{85}\times\left(\dfrac{11}{19}+\dfrac{12}{19}-\dfrac{42}{19}\right)\)

\(=\dfrac{31}{85}\times\dfrac{-19}{19}\)

\(=\dfrac{31}{85}\times-1\)

\(=-\dfrac{31}{85}\)

c) \(\dfrac{16}{53}:\dfrac{17}{9}-\dfrac{16}{53}:\dfrac{17}{8}\)

\(=\dfrac{16}{53}:\left(\dfrac{9}{17}-\dfrac{8}{17}\right)\)

\(=\dfrac{16}{53}:\dfrac{1}{17}\)

\(=\dfrac{16}{901}\)

c) \(\dfrac{1}{5}\times\dfrac{12}{31}\times\dfrac{4}{3}+\dfrac{19}{31}\times\dfrac{4}{15}\)

\(=\dfrac{4}{15}\times\dfrac{12}{31}+\dfrac{19}{31}\times\dfrac{4}{15}\)

\(=\dfrac{4}{15}\times\left(\dfrac{12}{31}+\dfrac{19}{31}\right)\)

\(=\dfrac{4}{15}\times\dfrac{31}{31}\)

\(=\dfrac{4}{15}\times1\)

\(=\dfrac{4}{15}\)

a: =18/29*(25/37+12/37)

=18/29

b: =31/85(11/19+12/19-42/19)

=-31/85

c; =16/53(9/17+8/17)=16/53

d: =4/15(12/31+19/31)=4/15

= 53 x (172 - 84 + 12 )

= 53. 100

=5300

53 x 172 - 53 x 84 + 12 x 53

= 53 x (172 - 84 + 12)

= 53 x 100

= 5300.

Nếu đúng xin like

53.172-53.84+12.53

= 53.(172-84+12)

=53.100

=5300

47 x 83 + 21 x 53 + 47 x 17 - 79 x 53

= 47 x (83 + 17) + 53 x (21 - 79)

= 47 x 100 + 53 x (-58)

= 4700 - 3074

= 1626

Chưa học số âm

\(47.83+21.53+47.17-79.53\)

\(=47.\left(83+17\right)+53.\left(79+21\right)\)

\(=47.100+53.100\)

\(=4700+5300\)

\(=10000\)