a)  66 . 25 + 5 . 66 + 66 . 14 + 33. 66

= 66 . ( 25 + 5 + 14 + 33 )

= 66 . 77

= 5082

b) 35 . 23 + 35 . 41 + 64 . 65

= 35 . ( 23 + 41 ) + 64 . 65

= 35 . 64 + 64 . 65

= 64 . ( 35 + 65 )

= 64 . 100

= 6400

c) 29 . 87 - 29 . 23 + 64 . 71

= 29 . ( 87 - 23 ) + 64 . 71

= 29 . 64 + 64 . 71

= 64 . ( 29 + 71 )

= 64 . 100

= 6400

66 x 25 + 5 x 66 + 66 x 14 + 33 x 66

= (25 + 5 + 14 + 33) x 66

= 77 x 66

= 5082

35 x 23 + 35 x 41 + 64 x 65

= [(23 + 41) x 35] + 64 x 65

= (64 x 35) + 4160

= 2240 + 4160

= 6400

29 x 87 - 29 x 23 + 64 x 71

= [(87 - 23) x 19] + 64 x 71

= (64 x 19) + 64 x 71

= 64 x 19 + 64 x 71

= (19 + 71) x 64

= 90 x 64

= 5760

cho mik sửa lại câu c

29 x 87 - 29 x 23 + 64 x 71

= (87 - 23) x 29 + 64 x 71

= 64 x 29 + 64 x 71

= 64 x (29 + 71)

= 64 x 100

= 6400

\(=29.\left(87-23\right)+64.71=29.64+64.71=64.\left(29+71\right)=64.100=6400\)

\(29.87-29.23+64.71\\ =29.\left(87-23\right)+64.71\\ =29.64+62.71\\ =\left(29+71\right).64\\ =100.64\\ =6400\)

a,29.(87-23)+64.71=29.64+64.71=64.(29+71)=64.100=6400

b,19.(27+20)+47.81=19.47+47.81=47.(19+81)=47.100=4700

c,87.(23+70)+13.93=87.93+13.93=93.(87+13)=93.100=9300

tick nha bạn

đây có phải đề cương?

l6

a.65.35

b.86.28

c.172.03

chúc hok tốt! =))

29.87-29.23+64.71

=29.(87-23)+64.71

=29.64+64.71

=64.(29+71)

=64.100

=6400

nhé bạn. *** mk nha

=29.87-23+71

=29.(87+23)-71

=29.110-71

=29.39

=1131

k cho minh nhe bạn

Tinh nhanh : 

a) 5.23+35.41+64.65

=5.23+5.7.41+64.13.5

=5.(23+7.41+64.13)

=5.(23+287+832)

=5.(310+832)

=5.1142

=5710

1)

a) 35.23 + 35.41 + 64.65 = 35(23+41) + 64.65 = 35 . 65 + 64.65 =65. 99 = 65(100 - 1 ) = 6500 - 65 = 6435

b) 29.87 - 29.23 + 64.71 = 29(87-23) + 64.71 = 29.64 + 64.71 = 64(71+29) = 64.100= 6400

c) 48.19 + 48.115 + 134.52 = 48(19+115) + 134.52 = 48 . 134+134.52=134(52+48)=134.100=13400

d) 27.121 - 87.27 + 73.34 = 27(121-87) +73 .34 = 27 .34 + 73.34 = 34(73+27)=34.100=3400

e) 125.98-125.46-52.25 = 125(98-46) -52.25 = 125 . 52 - 52.25 =52(125-25) =52.100=5200

f)136.23 + 136.17 - 40.36 = 136(23+17) - 40.36 = 136.40 -40.36 = (136-36)40 = 100.40=4000

g) 17.93 + 116.83 + 17.23 = 17(93+23) + 116.83 = 17.116 + 116.83 =116(83+17) = 116.100=11600

h)19.27 +47.81 + 19.20 = 19(27+20) + 47.81 = 19. 47 + 47.81 = 47(81+19)=47.100 = 4700

i) 87.23 + 13.93 + 70.87 = 87(23+70) + 13.93 = 87 .93 + 13.93 = 93(87+13)=93.100=9300

2)Tìm x

a) [(6x-39):37].4 = 12 

(6x - 39) : 37 = 12 : 4 = 3

x =(3.37 + 39): 6 = 25

b) ( x : 3 - 4 ) .5=15

x : 3 -4 = 3

x = (3+4).3 = 21

c) 128 - 3(x+4) =23

3x + 12 = 128 -23 = 105

x = (105-12):3 = 31

d) (3x - 3⁴).7³=2.7⁴

3x - 81 = 2.7⁴:7³=2.7=14

x =(81 + 14 ) : 3= \(31\frac{2}{3}\)

e) x - [42 + (-28) ] = -8 

x - 14 = -8 

x- 14 + 14 = -8 + 14 

x = 6

một hằng dài

1. Tính nhanh:

a, 35.23+35.41+64.65

= 35. (23+41) +64.65

= 35. 64 + 64.65

= 64. ( 35 + 65 )

= 64 . 100

= 6400

b, 29.87 - 29.23 + 64.71

= 29.(87-23) + 64.71

= 29.64 + 64.71

= 64.(29 + 71)

= 64.100

= 6400

c, 48.19 + 48.115 + 134.52

= 48.(19 + 115) + 134.52

= 48.134 + 134.52

= 134.(48 + 52)

= 134.100

= 13400

d, 27.121 - 87.27 + 73.34

= 27.(121 - 87) + 73.34

= 27.34 + 73.34

= 34.(27 + 73)

= 34.100

= 3400

e, 125.98 - 125.46 - 52.25

= 125.(98 - 46) - 52.25

= 125.52 - 52.25

= 52.(125 - 25)

= 52.100

= 5200

f, 136.23 + 136.17 - 40.36

= 136.(23 + 17) - 40.36

= 136.40 - 40.36

= 40.(136 - 36)

= 40.100

= 4000

g, 17.93 + 116.83 + 17.23

= 17.(93+23) + 116.83

= 17.116 + 116.83

= 116.(17 + 83)

= 116.100

= 11600

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