Question

Tinh bang cách hợp lý nhất 

A,39×8+60×2+21×8              b,12×53+53×172-53×84

C,35×34+35×86+65×75+65×67+65×45

D,36×28+36×82+64×69+64×41

Answer 1

a, 39 . 8 + 60 . 2 + 21 . 8

= 39 . 8 + 15 . 4 . 2 + 21 . 8

= 39 . 8 + 15 . 8 + 21 . 8

= 8 . ( 39 + 15 + 21 )

= 8 . 75

= 600

b, 12 . 53 + 53 . 172 - 53 . 84

= 53 . ( 12 + 172 - 84 )

= 53 . 100

= 5300

c, 35 . 34 + 35 . 86 + 65 . 75 + 65. 67 + 65.45

= 35 . ( 34 + 86 ) + 65 . ( 75 + 67 + 45 )

= 35 . 120 + 65 . 187

= 4200 + 12155

= 16355

d, 36 . 28 + 36 . 82 + 64 . 69 + 64 . 41

= 36 . ( 28 + 82 ) + 64 . ( 69 + 41 )

= 36 . 110 + 64 . 110

= 110 . ( 36 + 64 )

= 110 . 100

= 11000

Answer 2

a, 39 . 8 + 60 . 2 + 21 . 8

= 39 . 8 + 15 . 4 . 2 + 21 . 8

= 39 . 8 + 15 . 8 + 21 . 8

= 8 . ( 39 + 15 + 21 )

= 8 . 75

= 600

b, 12 . 53 + 53 . 172 - 53 . 84

= 53 . ( 12 + 172 - 84 )

= 53 . 100

= 5300

c, 35 . 34 + 35 . 86 + 65 . 75 + 65. 67 + 65.45

= 35 . ( 34 + 86 ) + 65 . ( 75 + 67 + 45 )

= 35 . 120 + 65 . 187

= 4200 + 12155

= 16355

d, 36 . 28 + 36 . 82 + 64 . 69 + 64 . 41

= 36 . ( 28 + 82 ) + 64 . ( 69 + 41 )

= 36 . 110 + 64 . 110

= 110 . ( 36 + 64 )

= 110 . 100

= 11000