a) (15 +35) : 5 = ?

Cách 1: (15 +35) : 5

= 50 : 5 = 10

Cách 2: (15 +35) : 5

= 15 : 5 + 35 : 5

= 3 + 7 = 10

+) (80 +4) : 4 = ?

Cách 1:(80 +4) : 4

= 84 : 4 = 21

Cách 2:(80 +4) : 4

= 80 : 4 + 4 :4 = 20 +1 = 21

b) 18 : 6 + 24 : 6 = ?

Cách 1: 18 : 6 + 24 : 6

= 3 + 4 = 7

Cách 2: (18 + 24) : 6

= 42 : 6 = 7

+) 60 : 3 + 9 : 3 =?

Cách 1: 60 : 3 + 9 : 3

= 20 + 3 = 23

Cách 2: 60 : 3 + 9 : 3

=(60 +9) : 3 = 23

a) (15 +35) : 5 = ?

Cách 1: (15 +35) : 5

= 50 : 5 = 10

Cách 2: (15 +35) : 5

= 15 : 5 + 35 : 5

= 3 + 7 = 10

+) (80 +4) : 4 = ?

Cách 1:(80 +4) : 4

= 84 : 4 = 21

Cách 2:(80 +4) : 4

= 80 : 4 + 4 :4 = 20 +1 = 21

b) 18 : 6 + 24 : 6 = ?

Cách 1: 18 : 6 + 24 : 6

= 3 + 4 = 7

Cách 2: (18 + 24) : 6

= 42 : 6 = 7

+) 60 : 3 + 9 : 3 =?

Cách 1: 60 : 3 + 9 : 3

= 20 + 3 = 23

Cách 2: 60 : 3 + 9 : 3

=(60 +9) : 3 = 23

1.

A.16

B.102

2.

SSH=( 80-4):4+1=20

TỔNG A= (80+4)*20:2=840

42 : 6 = 7        48 : 6 = 8        6 : 6 = 1        12 : 3 = 4

18 : 6 = 3        54 : 6 = 9        30 : 6 = 5        12 : 4 = 3

Trả lời

a) 9 . 24 . 25 = 9 . 600 = 5400

b) 12 . 125 . 54 = 1500 . 54 = 81000

c) 64 . 125 . 875 = 8000 . 875 = 7000000

d) 425 . 7 . 4 - 170 . 60 = 11900 - 10200 = 1700

e) 8 . 9 . 14 . 6 . 17 . 12 . 19 . 4 . 18 = 

a) 5400

b) 81000

c) 7000000

d) 1700

e) 15684492672

^.^

a) 9 . 24 . 25 = 3.3.3.4.2.25 = (25.4).(3.3.3.2) = 100.54 = 5 400
b) 12 . 125 . 54 = 4.3.125.2.3.3.3 = (125.2.4).(3.3.3.3) = 1000.81 = 81 000
c) 64 . 125 . 875 = (125.64).875 = 8000.875 = 7 000 000
d) 425 . 7 . 4 – 170 . 60 = 25.17.7.4 - 2.5.17.4.3.5 = 25.17.7.4 - 25.17.6.4 = 25.17.4.(7-6) = (25.4).17 = 100.17 = 1 700 

Đề bài câu e sai rồi bn, như này mới đúng:

e) 8 . 9 . 14 + 6 . 17 . 12 + 19 . 4 . 18 = (2.2.2.3.3).2.7 + (2.3.2.2.3).17 + (2.2.2.3.3).19 = 72.14 + 72.17 + 72.19 = 72.(14+17+19)

= 72.50 = 36.2.50 = 36.100 = 3 600
 

a,9.3.4.25

= 27.100

= 2700

b, 12.125.54

= 3.4.125.54

= 125.4.3.54

= 500.162

= 81000

c: \(=72\cdot14+72\cdot7+72\cdot19=72\cdot40=2880\)

d: \(=1700\cdot7-1700\cdot6=1700\)

e: Số số hạng là (65-1)/4+1=17(số)

Tổng là: \(\dfrac{65+1}{2}\cdot17=33\cdot17=561\)

cứu

a) 10; 13; 18; 26; 36; 52...

c) 0; 1; 4; 9; 16; 25...

m) 1; 4; 9; 16; 25; 36; 49; 64...

p) 1; 3; 9; 27; 81; 243...

a)=2 b)=3

a: \(=\left(\dfrac{4}{9}+\dfrac{5}{9}\right)+\left(\dfrac{1}{8}+\dfrac{7}{8}\right)=1+1=2\)

b: \(=\left(\dfrac{1}{6}+\dfrac{4}{6}+\dfrac{7}{6}\right)+\left(\dfrac{5}{12}+\dfrac{7}{12}\right)=2+1=3\)

a; \(\dfrac{1}{4}\) + \(\dfrac{2}{5}\) + \(\dfrac{6}{8}\) + \(\dfrac{9}{15}\) + \(\dfrac{8}{1}\)

= (\(\dfrac{1}{4}\) + \(\dfrac{6}{8}\)) + (\(\dfrac{2}{5}\) + \(\dfrac{9}{15}\)) + \(\dfrac{8}{1}\)

= (\(\dfrac{1}{4}\) + \(\dfrac{3}{4}\)) + (\(\dfrac{2}{5}\) + \(\dfrac{3}{5}\)) + 8

=  1 + 1 + 8

=  2 + 8

= 10

b; \(\dfrac{1}{2}\) + \(\dfrac{2}{4}\) + \(\dfrac{3}{6}\) + \(\dfrac{4}{8}\) + \(\dfrac{5}{10}\) + \(\dfrac{6}{12}\) + \(\dfrac{7}{14}\) + \(\dfrac{8}{16}\) + \(\dfrac{10}{20}\)

=  \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) x (\(\dfrac{2}{2}\) + \(\dfrac{3}{3}\) + \(\dfrac{4}{4}\) + \(\dfrac{5}{5}\)+ \(\dfrac{6}{6}+\dfrac{7}{7}+\dfrac{8}{8}\) + \(\dfrac{10}{10}\))

= \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) x (1 + 1 +1 + 1+ 1+ 1+ 1 +1)

= \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) x 1 x 8

= \(\dfrac{1}{2}\) + \(\)\(\dfrac{1}{2}\) x 8

= \(\dfrac{1}{2}\) + 4

= \(\dfrac{9}{2}\) 

c; \(\dfrac{1}{10}\) + \(\dfrac{4}{20}\) + \(\dfrac{9}{30}\)+\(\dfrac{16}{40}+\dfrac{25}{50}+\dfrac{36}{60}+\dfrac{49}{70}+\dfrac{64}{80}+\dfrac{81}{90}\)

= \(\dfrac{1}{10}+\dfrac{2}{10}+\dfrac{3}{10}+\dfrac{4}{10}+\dfrac{5}{10}+\dfrac{6}{10}+\dfrac{7}{10}+\dfrac{8}{10}+\dfrac{9}{10}\)

= \(\dfrac{1+2+3+4+5+6+7+8+9}{10}\)

=  \(\dfrac{\left(1+9\right)+\left(2+8\right)+\left(3+7\right)+\left(4+6\right)+5}{10}\)

= \(\dfrac{10+10+10+10+5}{10}\)

= \(\dfrac{\left(10+10+10+10\right)+5}{10}\)

= \(\dfrac{10\times4+5}{10}\)

= \(\dfrac{45}{10}\)

= \(\dfrac{9}{2}\)

a; \(\dfrac{1}{4}\) + \(\dfrac{2}{5}\) + \(\dfrac{6}{8}\) + \(\dfrac{9}{15}\) + \(\dfrac{8}{1}\)

  = (\(\dfrac{1}{4}\) + \(\dfrac{6}{8}\)) + (\(\dfrac{2}{5}\) + \(\dfrac{9}{15}\)) + 8

= (\(\dfrac{1}{4}\) + \(\dfrac{3}{4}\)) + (\(\dfrac{2}{5}\) + \(\dfrac{3}{5}\)) + 8

= 1 + 1 + 8

= 2 + 8

= 10

b; \(\dfrac{1}{2}\) + \(\dfrac{2}{4}\) + \(\dfrac{3}{6}\) + \(\dfrac{4}{8}\) + \(\dfrac{5}{10}\) + \(\dfrac{6}{12}\) + \(\dfrac{7}{14}\) + \(\dfrac{8}{16}\) + \(\dfrac{9}{18}\) + \(\dfrac{10}{20}\)

= \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\)

= \(\dfrac{1}{2}\) x 10

= 5

c; \(\dfrac{1}{10}\) + \(\dfrac{4}{20}\) + \(\dfrac{9}{30}\)+\(\dfrac{16}{40}+\dfrac{25}{50}+\dfrac{36}{60}+\dfrac{49}{70}+\dfrac{64}{80}+\dfrac{81}{90}\)

= \(\dfrac{1}{10}+\dfrac{2}{10}+\dfrac{3}{10}+\dfrac{4}{10}+\dfrac{5}{10}+\dfrac{6}{10}+\dfrac{7}{10}+\dfrac{8}{10}+\dfrac{9}{10}\)

= \(\dfrac{1+2+3+4+5+6+7+8+9}{10}\)

=  \(\dfrac{\left(1+9\right)+\left(2+8\right)+\left(3+7\right)+\left(4+6\right)+5}{10}\)

= \(\dfrac{10+10+10+10+5}{10}\)

= \(\dfrac{\left(10+10+10+10\right)+5}{10}\)

= \(\dfrac{10\times4+5}{10}\)

= \(\dfrac{45}{10}\)

= \(\dfrac{9}{2}\)