7x21+28-49=7x21-21=(7-1)x21=6x21=126

bằng 126 na

\(\dfrac{20\cdot2^4+12\cdot2^4-48\cdot2^2}{2^6}\)

\(=\dfrac{2^6\cdot5+2^6\cdot3-2^6\cdot3}{2^6}\)

=5

a) (137x25-25x37):10

=25x(137-37):10

=25x100:10

=2500:10

=250

b) 2/7x21/4-2/7:13/4

=2/7x21/4-2/7x4/13

=2/7x(21/4-4/13)

=2/7x257/52

=257/182

c)(124x237+152):(870+235x122)

=(29388+152):(870+28670)

=29540:29540

=1

a) (137 x 25 - 25 x 37 ) : 10 = (25 x (137 - 37) ) : 10

                                       = (25 x 100) : 10

                                       = 2500 : 10

                                       = 250

a)=(3425-925):10

=25200:10

=250

b)=3/2-8/91

=257/182

c)=(29388+152):(870+28670)

=29540:29540

=1

d)=1161+1539/72

=2700/72=75/2

e)=10/77+45/77x9/7

=10/77+405/539

=475/539

li ke cho mình nha Lam Le thi

a. -2/7 x 21/8

= -3/4

b. -3/25:6

= -3/25 x 1/6

= -1/50

12 x 24 - 24

= (12 - 1) x 24

= 11 x 24

= 264

  12 x 24 - 24 

=   288    - 24

=        264

12x24-24=

12x24=286-24=262

sai nhé

Bạn An viết sai đó bạn.

Nhơ

viết sai

\(x+\frac{3}{7}\times\frac{21}{9}=5\)

\(\Rightarrow x+\frac{3}{7}\times\frac{7}{3}=5\)

\(\Rightarrow x+1=5\)

\(\Rightarrow x=5-1=4\)

\(X+1=5\)

\(X=5-1\)

\(X=4\)

VẬY X=4 

K NHÁ BN

X+\(\frac{3}{7}\)x\(\frac{21}{9}\)=5

X+1=5

X=4

Vay X=.. 

lan sau viet p/s ban nhin o thanh cong cu co cai chu z lon nguoc day bam vao roi chon

= 3/4 : 5/8 = 6/5

= 15/8 - 1/3 + 1/6 = 37/24 + 1/6 = 41/23

= 7/15 + 1/2 = 29/30

mk có giải cho bạn lần trc rồi ạ!! bạn xem lại đi ạ ;-;"

\(\dfrac{4}{7}x\dfrac{21}{6}x\dfrac{8}{5}=\dfrac{16}{5}\)

\(\dfrac{15}{8}-\dfrac{4}{9}x\dfrac{6}{8}+\dfrac{1}{6}=\dfrac{41}{24}\)

\(\dfrac{7}{15}+\left(\dfrac{5}{6}-\dfrac{1}{3}\right)=\dfrac{29}{30}\)

=76 bn nhe

12x24-6x52+100

=288-312+100

=76

12x24=288.

6x52=312.

288-312= -24.

-24+100=76.