=(1+3+5+7+...+2007).0

=0

=(1+3+5+7+........+2007).(125125.127-127127.125)

=(1+3+5+...........+2007).      0

=0

tk mk nha

(1+3+5+7+.......+2007).(125125.127-127127.125)

=(1+3+5+7+........+2007).0

=0

Theo bài ra , ta có :

(1+3+5+7+..........+2007).(125125.127-127127.125)

= (1+3+5+7+..........+2007) . (125 . 1001 . 127 - 127.1001.125)

= (1+3+5+7+..........+2007) . 0 

= 0 

Đáp số : 0 

(1+3+5+7+..........+2007).(125125.127-127127.125)

= (1+3+5+7+..........+2007) . (125 . 1001 . 127 - 127.1001.125)

= (1+3+5+7+..........+2007) . 0 

= 0 

ta có: 125125.127-127127.125=0

suy ra biểu thức trên bằng 0

1, (1+3+5+....+2007+2009+2011)(125125.127-127127.125)

=  (1+3+5+....+2007+2009+2011)(125.1001.127-127127127.125)

=  (1+3+5+....+2007+2009+2011)(125.127127-127127.125)

=  (1+3+5+....+2007+2009+2011)  . 0

=0 

còn bài 2 đề hình như thiếu nha bn 

chúc bn học tốt!

mình viết nhầm 720:[41-(2x-5)=120

Giải

1)Thực hiện phép tính :

(1+3+5+7+..+2007+2009+2011) (125125.127-127127.125)

=(1+3+5+7+...+2007+2009+2011).(125.101.127-127.101.125)

=(1+3+5+7+...+2007+2009+2011).0

=0 (vì số nào nhân với 0 cũng bằng 0)

2)Tìm x, biết:

720:[41-(2x-5)]+120

Bài 2 thiếu vế phải nha bạn !

Bạn ghi thêm đề ở phẩn trả lời ik, rồi mk làm giúp choa !

Mơn bạn nha !

\(a,1999-2000+1=\left(1999+1\right)-2000=2000-2000=0\\ b,450:5+550:5=\left(450+550\right):5=1000:5=200\\ c,188\times7+188\times4-188=188\times\left(7+4-1\right)=188\times10=1880\)

a,1999−2000+1=(1999+1)−2000=2000−2000=0b,450:5+550:5=(450+550):5=1000:5=200c,188×7+188×4−188=188×(7+4−1)=188×10=1880

a) 1999 - 2000 + 1

= ( 1999 + 1 ) - 2000

= 2000 - 2000

= 0

b) 450 : 5 + 550 : 5

= ( 450 + 550 ) : 5 

= 1000 : 5

= 200

c) 188 x 7 + 188 x 4 - 188

= ( 7 + 4 - 1 ) x 188

= 10 x 188

= 1880

a) \(\dfrac{3}{5}\times\dfrac{17}{21}+\dfrac{17}{21}\times\dfrac{2}{5}\)

\(=\dfrac{17}{21}\times\left(\dfrac{3}{5}+\dfrac{2}{5}\right)\)

\(=\dfrac{17}{21}\times1\)

\(=\dfrac{17}{21}\)

b) \(\dfrac{15}{8}:\dfrac{5}{20}-\dfrac{7}{8}:\dfrac{1}{4}\)

\(=\dfrac{15}{8}\times\dfrac{20}{5}-\dfrac{7}{8}\times4\)

\(=\dfrac{15}{8}\times4-\dfrac{7}{8}\times4\)

\(=4\times\left(\dfrac{15}{8}-\dfrac{7}{8}\right)\)

\(=4\times1\)

\(=4\)

a, =(3/5+2/5)x17/21

=1x17/21

=17/21

a) \(\dfrac{3}{5}\) x \(\dfrac{17}{21}+\dfrac{17}{21}\) x \(\dfrac{2}{5}\)

\(=\left(\dfrac{3}{5}+\dfrac{2}{5}\right)\) x \(\dfrac{17}{21}\)

\(=\dfrac{5}{5}\) x \(\dfrac{17}{21}\)

\(=1\) x \(\dfrac{17}{21}\)

\(=\dfrac{17}{21}\)

b) \(\dfrac{15}{8}:\dfrac{5}{20}-\dfrac{7}{8}:\dfrac{1}{4}\)

\(=\dfrac{15}{8}:\dfrac{1}{4}-\dfrac{7}{8}:\dfrac{1}{4}\)

\(=\left(\dfrac{15}{8}-\dfrac{7}{8}\right):\dfrac{1}{4}\)

\(=\dfrac{8}{8}:\dfrac{1}{4}\)

\(=1:\dfrac{1}{4}\)

\(=\dfrac{1}{1}:\dfrac{1}{4}\)

\(=\dfrac{1}{1}\) x \(\dfrac{4}{1}\)

\(=\dfrac{4}{1}\)

\(=4\)

\(\dfrac{8}{13}+\dfrac{4}{9}+\dfrac{1}{3}+\dfrac{5}{13}+3\)

\(=1+\dfrac{7}{9}+3\)

\(=4+\dfrac{7}{9}=\dfrac{43}{9}\)

`39/16 : 5/8 - 7/16 : 5/8`

`=39/16 xx 8/5- 7/16 xx 8/5`

`=8/5 xx (39/16 - 7/16)`

`= 8/5 xx2`

`= 16/5`

__

` 4/3 xx 9/8 - 4/3 xx 3/8`

`=4/3 -(9/8 - 3/8)`

`= 4/3 xx 3/4`

`=1`

\(a,\\ \dfrac{39}{16}:\dfrac{5}{8}-\dfrac{7}{16}:\dfrac{5}{8}\\ =\dfrac{39}{16}\cdot\dfrac{8}{5}-\dfrac{7}{16}\cdot\dfrac{8}{5}\\ =\dfrac{8}{5}\cdot\left(\dfrac{39}{16}-\dfrac{7}{16}\right)=\dfrac{8}{5}\cdot2=\dfrac{16}{5}\\ b,\\ \dfrac{4}{3}\cdot\dfrac{9}{8}-\dfrac{4}{3}\cdot\dfrac{3}{8}=\dfrac{3}{2}-\dfrac{1}{2}=1\)

a)

`39/16:5/8-7/16:5/8`

`=(39/16-7/16):5/8`

`=32/16xx8/5`

`=2xx8/5`

`=16/5`

b)

`4/3xx9/8-4/3xx3/8`

`=4/3xx(9/8-3/8)`

`=4/3xx6/8`

`=4/3xx3/4`

`=1`

A. 64 : 16 = 4

B. 210 : 30 = 7

C. 504 : 56 = 9

D. 115 : 23 = 5

Sao lại đổi câu hỏi thế này ? Bạn vui lòng đăng câu hỏi khác ạ !

A. 64 : 16 = 4

B. 210 : 30 = 7

C. 504 : 56 = 9

D. 115 : 23 = 5

Bài 2: Tính bằng cách thuận tiện nhất

\(\text{a. 1255 + 436 + 145}\)

\(=\left(1255+145\right)+436\)

\(=1400+436\)

\(=1836\)

\(\text{b. 142 x 12 + 142 x 18}\)

\(=142\times\left(12+18\right)\)

\(=142\times30\)

\(=4260\)

\(\text{c. 4 x 18 x 25}\)

\(=\left(25\times4\right)\times18\)

\(=100\times18\)

\(=1800\)

Bài 2:

a: \(=1400+436=1836\)

b: =142(12+18)

=142*30

=4260

c: \(=100\cdot18=1800\)

Bài 3:

a: \(41m^219dm^2>409dm^2\)

b: \(90000cm^2< 90m^2\)

c: \(30m^26dm^2< 3060dm^2\)

d: \(8012cm^2>8dm^212cm^2\)

e: \(5dm^29cm^2=509cm^2\)

f: \(3940dm^2=39m^240dm^2\)

g: \(300m^26dm^2>3006dm^2\)

h: \(2009cm^2< 21dm^2\)