12.68+34.18-34-142

12.2.34+34.18-34.1-142

=24.34+34.18-34.1-142

=34.(24+18-1)-142

=34.41-142

=1394-142

=1252

giống bài mk đã làm nhưng dù sao cx cảm ơn bn

12. 68 + 34. 18 - 34- 142

= 12. 34 .2 +  34 .18 - 34 - 142

= 24 .34 + 34 .18 - 34 .1 -142

= 34 .(24+18-1) - 142

=34 .41 - 142

= 1394 - 142

=1252

12. 68 + 34. 18 - 34- 142

=12.2.34+34.18+108

=24.34+34.18+108

=34.(24+18)+108

=34.42+108

=1428+108

=1536

5³ + 3⁴ - 14²

= 125 + 81 - 196

= 206 - 196

= 10

theo mình nghĩ là thế :))

\(5^3+3^4-14^2=125+81-196=10\)

4828

4828

Dạ em cảm ơn ạ

(456-142)x176:4

=314x176:4

=13816 nhé

13816 nhé

( 456 - 142) x 176 : 4

=314 x 176 : 4

=314 x 44

=13816

a ) A = 1 2.3 + 2 3.4 + 1 4.5 + 1 5.6 + 1 6.7 + 1 7.8

1 2 − 1 3 + 1 3 − 1 4 + 1 4 − 1 5 + 1 5 − 1 6 + 1 6 − 1 7 + 1 7 − 1 8 = 3 8

b ) B = 3 1.4 + 3 4.7 + 3 7.10 + 3 10.13 + 3 13.16 + 3 16.19

= 1 − 1 4 + 1 4 − 1 7 + 1 7 − 1 10 + 1 10 − 1 13 + 1 13 − 1 16 + 1 16 − 1 19 = 18 19

c ) C = 1 3 3 1.4 + 3 4.7 + 3 7.10 + 3 10.13 + 3 13.16 + 3 16.19

= 1 3 1 − 1 4 + 1 4 − 1 7 + 1 7 − 1 10 + 1 10 − 1 13 + 1 13 − 1 16 + 1 16 − 1 19 = 6 19

d ) D = 2 4 + 2 28 + 2 70 + 2 130 + 2 208 + 2 304

= 2 3 3 1.4 + 3 4.7 + 3 7.10 + 3 10.13 + 3 13.16 + 3 16.19 = 12 19

Sửa đề: \(98+99+\dfrac{142}{144}\) \(\rightarrow\dfrac{98}{99}+\dfrac{143}{144}\)  

Giải:

\(A=\dfrac{2}{3}+\dfrac{14}{15}+\dfrac{34}{35}+\dfrac{62}{63}+\dfrac{98}{99}+\dfrac{143}{144}+\dfrac{194}{195}\) 

\(A=\left(1-\dfrac{1}{3}\right)+\left(1-\dfrac{1}{15}\right)+\left(1-\dfrac{1}{35}\right)+...+\left(1-\dfrac{1}{195}\right)\) 

\(A=7-\left(\dfrac{1}{3}+\dfrac{1}{15}+\dfrac{1}{35}+...+\dfrac{1}{195}\right)\) 

\(A=7-\left(\dfrac{1}{1.3}+\dfrac{1}{3.5}+\dfrac{1}{5.7}+...+\dfrac{1}{13.15}\right)\) 

\(A=7-\left[\dfrac{1}{2}.\left(\dfrac{2}{1.3}+\dfrac{2}{3.5}+\dfrac{2}{5.7}+...+\dfrac{2}{13.15}\right)\right]\) 

\(A=7-\left[\dfrac{1}{2}.\left(\dfrac{1}{1}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{13}-\dfrac{1}{15}\right)\right]\) 

\(A=7-\left[\dfrac{1}{2}.\left(\dfrac{1}{1}-\dfrac{1}{15}\right)\right]\) 

\(A=7-\left[\dfrac{1}{2}.\dfrac{14}{15}\right]\) 

\(A=7-\dfrac{7}{15}\) 

\(A=\dfrac{98}{15}\) 

Chúc bạn học tốt!

\(142-\left[50-\left(2^3.10-2.5\right)\right]\)

= \(142-\left[50-\left(80-10\right)\right]\)

= \(142-\left(50-70\right)\)

= \(142-\left(-20\right)\)

= \(162\)

\(142-\left[50-\left(2^3\cdot10-2\cdot5\right)\right]\)

\(=142-50+80+10\)

\(=72+90\)

=162

a) `27 .75 + 25.27 -150`

`=27 xx (75 + 25)-150`

`=27 xx 100-150`

`=2700-150`

`=2550`

b) `142-[50-(2^3 .10-2^3 .5)]`

`=142-[50-2^3 .(10-5)]`

`=142-(50-8 .5)`

`=142-(50-40)`

`=142-10`

`=132`

c) `375:{32-[4+(5.3^2-42)]}-14`

`=375:{32-[4+(45-42)]}-14`

`=375:[32-(4+3)]-14`

`=375: 25 -14`

`=15-14`

`=1`

a. 27 . 75 + 25 . 27 - 150

= 27. (75 + 25) - 150

= 27 . 100 - 150

= 2700 - 150

= 2550

b. 142 - [50 - (2³.10 - 2³.5)]

= 142 - [50 - (8 . 10 - 8 . 5)]

= 142 - {50 - [8 . (10 - 5)]} 

= 142 - (50 - 40)

= 142 - 10

= 132

c. 375 : {32 – [ 4 + (5. 3² – 42)]} – 14

= 375 : {32 – [ 4 + (5. 9 – 42)]} – 14

= 375 : {32 – [ 4 + (45 – 42)]} – 14

= 375 : {32 – [ 4 + 3]} – 14

= 375 : {32 –7} – 14

= 375 : 25 - 14

= 15 - 14

= 1

Bạn có thể viết rõ đề hơn được không???

Chúc bạn học tốt