14900

106

\(a,149\times\left(75+23+1+1\right)=149\times100=14900\)

\(b,13,25:\left(0,5+0,25+0,025\right)=\dfrac{53}{4}\times\dfrac{40}{31}=\dfrac{530}{31}\)

14900,106

kết quả là 16 nha bạn

49. (-23 + 2.x) = (-49).(-23 + 14)

49. (-23 + 2.x) = (-49). (-9)

49. (-23 + 2.x) = 441

     -23 + 2.x = 441 : 49

     -23 + 2.x = 9

             2.x = 9 - (-23)

            2.x = 32

              x = 32 : 2

              x = 16

đáp số: 16

1. a. (x-45).27=0

=> x-45=0

=> x=0+45

=> x=45

b. 23.(42-x)=23

=> 42-x=23:23

=> 42-x=1

=> x=42-1

=> x=41

2. A=26+27+28+29+30+31+32+33

= (26+33)+(27+32)+(28+31)+(29+30)

= 59+59+59+59

= 59 . 4

= 236

3. 997+37=997+3+34=1000+34=1034

49+149=49+1+148=50+148=198

   23 x 50 + 49 x 23 + 23

= 23 x 50 + 49 x 23 + 23 x 1 

= 23 x ( 50 + 49 + 1 )

= 23 x 100

= 2300

23 x 50 + 49 x 23 + 23

= 1150 + 1129 + 23

= 2302

23 x 50 + 49 x 23 + 23

= 23 x ( 50 + 49 + 1 )

= 23 x 100

= 2300

a)  2 3 + 2 5 − 2 9 4 3 + 4 5 − 4 9 = 2 1 3 + 1 5 − 1 9 4 1 3 + 1 5 − 1 9 = 1 2

b)  3 4 + 3 7 − 3 8 5 4 + 5 7 − 5 8 + 1 = 3 1 4 + 1 7 − 1 8 5 1 4 + 1 7 − 1 8 + 1 = 3 5 + 1 = 8 5

Ta có A = \(\dfrac{1}{42}+\dfrac{1}{56}+\dfrac{1}{72}+\dfrac{1}{90}+\dfrac{1}{110}+\dfrac{1}{132}\)

= \(\dfrac{1}{6\cdot7}+\dfrac{1}{7\cdot8}+\dfrac{1}{8\cdot9}+\dfrac{1}{9\cdot10}+\dfrac{1}{10\cdot11}+\dfrac{1}{11\cdot12}\)

= \(\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{10}+\dfrac{1}{10}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{12}\)

= \(\dfrac{1}{6}-\dfrac{1}{12}=\dfrac{1}{12}\) 

B = \(\dfrac{\dfrac{2}{29}-\dfrac{2}{39}+\dfrac{2}{49}}{\dfrac{23}{29}-\dfrac{23}{39}+\dfrac{23}{49}}=\dfrac{2\left(\dfrac{1}{29}-\dfrac{1}{39}+\dfrac{1}{49}\right)}{23\left(\dfrac{1}{29}-\dfrac{1}{39}+\dfrac{1}{49}\right)}=\dfrac{2}{23}\) 

Lại có \(\dfrac{2}{23}>\dfrac{2}{24}=\dfrac{1}{12}\) hay A < B

Vậy A < B

Cảm ơn bạn nhé!

a: =(-23+23)+230=230

b: =54(-124+24)=-5400

c: =-927+930=3

d: =(-351+51)+(-74-126)-149=-300-200-149=-649

e: \(=\dfrac{3^3\cdot\left(2^3+2^2+1\right)}{13}=3^3=27\)

\(a,=\left[\left(-23\right)+23\right]+230=0+230=230\\ b,=\left(-124\right).54+24.54\\ =54.\left[\left(-124\right)+24\right]=54.\left(-100\right)=-5400\)

a) (-23) + 230 + 23

=([-23] + 23) + 230

=0+230

=230

b)124. (-54) + 24 . 54

= ([-54 + 54]) + (124 + 24)

=0 + 48

=48

Đây chỉ là tham khảo, nếu có si sót thì xin lỗi 

Cảm ơn!

2 3 × 4 9 + 2 3 × 5 9 = 2 3 × 4 9 + 5 9

= 2 3 × 9 9 = 2 3 × 1 = 2 3

\(49\dfrac{8}{23}-\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)=49\dfrac{8}{23}-5\dfrac{7}{32}-14\dfrac{8}{23}=\left(49\dfrac{8}{23}-14\dfrac{8}{23}\right)-5\dfrac{7}{32}=35-5\dfrac{7}{32}=\dfrac{953}{32}\)