35  x 20 x 5           8 x 9 x 125         25 x 7 x 4    72:(8x3)

= 35 x ( 20  x5 )      = ( 8x125) x 9    = (25x4)x7    = 72: 24

= 35 x 100              = 1 000 x 9       = 100x7        = 3

= 3 500                  = 9  000            =700

(36x7):4

=36: 4 x 7 

= 9 x7

= 63 

35 x 20 x 5 = 35\(\times\)(20 \(\times\)5)= 35 \(\times\)100=3500

8 \(\times\)9 \(\times\) 125 =(8\(\times\) 125)\(\times\)9=1000\(\times\)9=9000

25 \(\times\)7\(\times\)4=(25 \(\times\)4)\(\times\)7=100\(\times\)7=700

72 : (8\(\times\)3)=72 : 8 x 3 =(72:8) x 3=9 x   3=27

(36 x 7) : 4 =36 x 7 : 4 =7 x (36 :4)=7 x 9=63

a: =428(36+64)=42800

b: =512(47-37)=5120

c: =72x100=7200

\(428×(36+64)\)

\(=428×100\)

\(=42800\)

\(512×(47-37)\)

\(=512×10\)

\(=5120\)

\(72×(4×25)\)

\(=72×100\)

\(=7200\)

\(\left(\dfrac{4+5}{9}\right)\text{×}\dfrac{3}{7}\)

\(=1\text{×}\dfrac{3}{7}\)

\(=\dfrac{3}{7}\)

Ta có:

a) ( 45 – 5 x 9 ) x 1 x 2 x 3 x 4 x 5 x 6 x 7

= (45 – 45) x 1 x 2 x 3 x 4 x 5 x 6 x 7

= 0 x 1 x 2 x 3 x 4 x 5 x 6 x 7

= 0

b) (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 8 x 8 – 8)

= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 64 – 8)

= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x 0

= 0

c) (36 – 4 x 9) : (3 x 5 x 7 x 9 x 11)

= (36 – 36) : (3 x 5 x 7 x 9 x 11)

= 0 : (3 x 5 x 7 x 9 x 11)

= 0

d) (27 – 3 x 9) : 9 x 1 x 3 x 5 x 7

= (27 – 27) : 9 x 1 x 3 x 5 x 7

= 0 : 9 x 1 x 3 x 5 x 7

=0

a) ( 45 – 5 x 9 ) x 1 x 2 x 3 x 4 x 5 x 6 x 7

= 0 x 1 x 2 x 3 x 4 x 5 x 6 x 7

b) (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 8 x 8 – 8)

= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x 0

c) (36 – 4 x 9) : (3 x 5 x 7 x 9 x 11)

= 0 : (3 x 5 x 7 x 9 x 11)

d) (27 – 3 x 9) : 9 x 1 x 3 x 5 x 7

= 0 : 9 x 1 x 3 x 5 x 7                                                                                                                  Nếu đúng thì k cho mình nhé bạn!

a,345x(24+75+1)=345x100=34500

b,(72x1567):8=1567x(72:8)=1567x9=14103

\(a.60\times\left(\frac{7}{12}+\frac{4}{15}\right)\)

\(=60\times\left(\frac{35}{60}+\frac{16}{60}\right)\)

\(=60\times\frac{51}{60}\)

\(=51\)

\(b.\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}\times\frac{5}{6}\times\frac{6}{7}\times\frac{7}{8}\times\frac{8}{9}\)

\(=\frac{1\times2\times3\times4\times5\times6\times7\times8}{2\times3\times4\times5\times6\times7\times8\times9}\)

\(=\frac{1}{9}\)

C1:

a. 786 x ( 32 +68)

= 786 x  100

= 78600

b. 2904 x 15 + 2904 x 35

= 43560 + 101640

= 145200

c.436 x 72 - 436 x 42

= 31392 - 18312

= 13080

d.194 x (87-7)

= 194 x 80

=15520

e.3332 : (4x49)

= 3332 : 196

= 17

f. 72 : 9 : 8

= (72 : 9) :8

= 1

g. (15 x 24) : 6

= 360 :6

= 60

m. 25 x(36 :9)

= 25 x 4

= 100

Cách 2:

a.786 x 32 + 786 x 68

= 25152 + 53448

= 78600

b. 2904 x ( 15 + 35)

= 2904 x 50

= 145200

c.436 x (72 -42)

= 436 x 30

= 13080

d.194 x 87 - 194 x7

= 16878 - 1358

= 15520

e. 3332 : (4 x 49)

= 3332 : 4 : 49

= 833 : 49 = 17

f. 72 : 9 :8

= 72 : (9 x8)

= 72 : 72

=1

g. (15 x 24) :6 

= 15 x (24 :6)

= 15 x 4

= 60

m. 25 x (36 :9)

= ( 25 x36 ):9

= 900 : 9

=100

ghi nhiều quá

a)1440:40 =36

b)205 x 13 =2665

c)2057

d)36 x 25 x 4 =3600

18 x 24 :9 =48

41 x 2 x 8 x 5 =3280

215 x 86 + 215 x 14 =21500

53 x 128 - 43 x 128 =1408

2/3 x 4/7 =8/21

2 x 3 x 4 / 2 x 3 x 4 x 5 =24/120

1 x 2 x 3 x 4  / 5 x 6 x 7 x 8=24/1680

x : 7/11 = 22

          x =22 x 7/11

          x =14

2/7 * x =2/3 

         x = 2/7 :2/3

         x = 20/21