a.\(\dfrac{27}{8}\)

b.\(\dfrac{37}{40}\)
c.\(\dfrac{5}{2}\)

d.\(\dfrac{7}{3}\)

e.5

g.\(\dfrac{53}{16}\)

Bài 1 :

a) \(\dfrac{3}{2}+\dfrac{5}{4}+\dfrac{5}{8}=\dfrac{12}{8}+\dfrac{10}{8}+\dfrac{5}{8}=\dfrac{12+10+5}{8}=\dfrac{27}{8}\)

b) \(\dfrac{4}{5}-\dfrac{3}{8}+\dfrac{2}{4}=\dfrac{32}{40}-\dfrac{15}{40}+\dfrac{20}{40}=\dfrac{32-15+20}{40}=\dfrac{37}{40}\)

c) \(3+\dfrac{6}{8}-\dfrac{5}{4}=\dfrac{3}{1}+\dfrac{6}{8}-\dfrac{5}{4}=\dfrac{24}{8}+\dfrac{6}{8}-\dfrac{10}{8}=\dfrac{20}{8}=\dfrac{5}{2}\)

d) \(\dfrac{5}{6}-\dfrac{1}{2}+2=\dfrac{5}{6}-\dfrac{1}{2}+\dfrac{2}{1}=\dfrac{5}{6}-\dfrac{3}{6}+\dfrac{12}{6}=\dfrac{14}{6}=\dfrac{7}{3}\)

e) \(\dfrac{3}{5}+\dfrac{6}{11}+\dfrac{7}{13}+\dfrac{2}{5}+\dfrac{16}{11}+\dfrac{19}{13}=\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{6}{11}+\dfrac{16}{11}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)=1+2+2=5\)

g) \(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{29}{32}+\dfrac{1}{4}+\dfrac{3}{21}+\dfrac{13}{32}=\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{29}{32}+\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{13}{32}=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{29}{32}+\dfrac{13}{32}\right)=1+1+\dfrac{21}{16}=2+\dfrac{21}{16}=\dfrac{53}{16}\)

a,3/2+5/4+5/8 = 12/8 + 10/8 + 5/8 = 27/8

b,4/5-3/8+2/4 = 32/40 - 15/40 + 20/40 = 37/40

c,3+6/8-5/4= 24/8 + 6/8 - 10/8 = 20/8 = 5/2

d,5/6-1/2+2 = 5/6 - 3/6 + 12/6 = 14/6 = 7/3

e,3/5+6/11+7/13+2/5+16/11+19/13 = ( 3/5+ 2/5) + ( 6/11 + 16/11) + ( 7/13 + 19/13) = 1 + 2 + 2 = 5

g,75/100+18/21+29/32+1/4+3/21+13/32 = 3/4 + 6/7 + 29/32 + 1/4 + 1/7 + 13/32=  ( 3/4 + 1/4) + ( 29/32 + 13/32) + ( 6/7 + 1/7)= 1 + 21/16 + 1 = 53/16

\(\left(19\frac{5}{8}:\frac{7}{12}-13\frac{1}{4}:\frac{7}{12}\right).\frac{4}{5}\)

\(=\left(\frac{157}{8}:\frac{7}{12}-\frac{53}{4}:\frac{7}{12}\right).\frac{4}{5}\)

\(=\left[\left(\frac{157}{8}-\frac{53}{4}\right):\frac{7}{12}\right].\frac{4}{5}\)

\(=\left[\frac{51}{8}:\frac{7}{12}\right].\frac{4}{5}\)

\(=\frac{153}{14}.\frac{4}{5}\)

\(=\frac{306}{35}\)

\(\left(\frac{-2}{5}+\frac{3}{7}\right)-\left(\frac{4}{9}+\frac{12}{20}-\frac{13}{35}\right)+\frac{7}{35}\)

\(=\frac{1}{35}-\frac{212}{315}+\frac{7}{35}\)

\(=\frac{1}{35}+\frac{-212}{315}+\frac{7}{35}\)

\(=\frac{9}{315}+\frac{-212}{315}+\frac{63}{315}\)

\(=\frac{-140}{315}=\frac{-4}{9}\)

\(\left(4\frac{5}{57}-3\frac{4}{51}+8\frac{13}{29}\right)-\left(3\frac{5}{57}-6\frac{16}{29}\right)\)

\(=\left(\frac{233}{57}-\frac{157}{51}+\frac{245}{29}\right)-\left(\frac{176}{57}-\frac{190}{29}\right)\)

\(=\frac{1941}{323}-\frac{-5726}{1653}\)

\(=\frac{14011}{1479}\)

a)29 . (19 – 13) – 19 . (29 – 13)

= 29 . 6 – 19 . 16

= 174 – 304

= –130.

b)31.(-18)+31.(-81)-31       

= 31. [-18 + (-81) - 1 ]

= 31. (-100)

= -3100

c)(7.3-3):(-6)  

(7.3-3):(-6)

= (21-3):(-6)

= 18 : (-6)

= 3

d)72:[(-6).2+4)]       

= 72 : ( -12 + 4 )

= 72 : -8

= -9

Bài 2:

a)(-12).47+(-12).52+(-12)       

= (-12).(47+52+1)

= -1200

b)13.(23+22)-3.(17+28)  

13 . (23 + 22) - 3 . (17 + 28)

= 13 . 45 - 3 . 45

= ( 13 - 3 ) . 45

= 10 . 45

= 450

c)18-10:(-2)-7   

= 18-5+7

= 13+7

= 20

d)99:[(-7).2+5)

1. Tính nhanh

a) 29 . (19 – 13) – 19 . (29 – 13)

= 29 . 6 – 19 . 16

= 174 – 304

= –130.

b) 31 . (-18) + 31 . (-81) - 31       

= 31. [-18 + (-81) - 1 ]

= 31. (-100)

= -3100

c) (7 . 3 - 3) : (-6)

= (21 - 3) : (-6)

= 18 : (-6)

= 3

d) 72 : [(-6) . 2 + 4)]       

= 72 : ( -12 + 4 )

= 72 : -8

= -9

2. Tính nhanh

a) (-12) . 47 + (-12) . 52 + (-12)

= (-12) . (47 + 52 + 1)

= (-12) . 100

= -1200        
b) 13 . (23 + 22) - 3 . (17 + 28)   

= 13 . 45 - 3 . 45

= (13 - 3) . 45

= 10 . 45

= 450
c) 18 - 10 : (-2) - 7   

= 18-5+7

= 13+7

= 20

d) 99 : [(-7) . 2 + 5]

= 99 : -9

= -11

Em nến gõ bằng công thức toán học em nhé. Như vậy mọi người nới hiểu đúng đề bài để trợ giúp cho em một cách tốt nhất em ạ!

a.C1:

15.12-3.5.10 = 180-150

=130

C2:

15.12-3.5.10=15.12-15.10

=15.(12-10)

=15.2=30

2 câu kia bạn từ lm nha.K mk nhé

a, C1 cach nhân tử chung :lấy 3x5 rồi có chung là 15

C2 tinh như bình thường

b, C2 mở 9(13+5) ra

c,C2 mở tất cả ngoặc ra rồi thấy mẫu chung náo thì ghép lại

k cho nha

a,15.12-3.5.10

=15.12 - 15 .10

=15(12-10)

=15.2

=30

c, 29 . ( 19 - 13 ) - 19 . ( 29 - 13 )

= 29.19-29.13-19.29-19.13

Tự làm nhé!

a) C1 : 15 . 12 - 3 . 5 . 10

= 180 - 15 . 10

= 180 - 150

= 30

C2 : 15 . 12 - 3 . 5 . 10

= 15 . 12 - 15 . 10

= 15 . ( 12 - 10 )

= 15 . 2

= 30

b) C1 : 45 - 9 . ( 13 + 5 )

= 45 - 9 . 18

= 45 - 162

= -117

C2 : 45 - 9 . ( 13 + 5 )

= 45 - 9 . 13 - 9 . 5

= 9 . 5 - 9 . 13 - 9 . 5

= ( 9 . 5 - 9 . 5 ) - 9 . 13

= 0 - 117

= -117

c) C1 : 29 . ( 19 - 13 ) - 19 . ( 29 - 13 )

= 29 . 6 - 19 . 16

= 174 - 304

= -130

C2 : 29 . ( 19 - 13 ) - 19 . ( 29 - 13 )

= 29 . 19 - 29 . 13 - 19 . 29 + 19 . 13

= ( 29 . 19 - 19 . 29 ) + ( 19 . 13 - 29 . 13 )

= 0 + [ 13 . ( 19 - 29 ) ]

= 0 + [ 13 . ( - 10 ) ]

= 0 + ( - 130 )

= -130

      a) 15.12-3.5.10                                                             b) 45 - 9 . (13 + 5)

    C1:=180 - 15 . 10          C2:=15 .12 - 15 .10              C1:= 45 - 9 . 18                     C1: = 45 - 9. 13 - 9. 5

          =180 - 150                  =15 . (12 - 10)                           =45 - 162                            =  45 - 9. 13 - 45

          =30                           =15 . 2 = 30                                 = -117                                 = 45 - 45 - 9. 13 

                                                                                                                                           =     0 - 117 = -117

     c) 29. ( 19 - 13 ) - 19.( 29 - 13)

 C1:= 29. 6 - 19. 16                            C2: = 29. 19 - 29. 13 - 19. 29 - 19. 13

      =   174 -   304                                     =    541  -   377   -    541  -     247

      =       -130                                           =    541  -   541   -  377 - 247

                                                                 =            0            -      130 = -130

to cung dang thac mac ne

a) C1: 15-12 . -3 . 5-10 

= 15 - (-36) .(-5) 

=15-180

=-165

C2: 15-(12.5) . [(-3).(-10)

=15-60.30

= 15 - 180

=-165

Dài quá bạn ơi nhiêu đây thoy nhé :-)