Tính hợp lý a\ 35 . 18 – 5 . 7 . 28 b\ 24 . [ 16 – 5 ] + 16. [ 24 – 5 ] c\ 31 . [ – 18 ] + 31 . [ -81 ] – 31 d\ 13 . [ 23 + 22 ] – 3 . [ 17 + 28 ]

0 bình luận về “Tính hợp lý a\ 35 . 18 – 5 . 7 . 28 b\ 24 . [ 16 – 5 ] + 16. [ 24 – 5 ] c\ 31 . [ – 18 ] + 31 . [ -81 ] – 31 d\ 13 . [ 23 + 22 ] – 3 . [ 17 + 28 ]”

1. a) 35 . 18 – 5 . 7 . 28

   = 35 . 18 – 35 . 28

   = 35 (18 – 28)

   = 35 . (-10)

   = -350

   b) 24 . (16 – 5) + 16. (24 – 5)

   = 24 . 16 – 24 . 5 + 16 . 24 – 16 . 5

   = (24 . 16 + 16 . 24) – (24 . 5 + 16 . 5)

   = [24 . (16 + 16)] – [5 . (24 + 16)]

   = (24 . 32) – (5 . 40)

   = 768 – 200

   = 568

   c)  31 . (- 18) + 31 . (-81) – 31

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

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

   = 31 . (-100)

   = -3100

   d) 13 . (23 + 22) – 3 . (17 + 28)

   = 13 . 45 – 3 . 45

   = 45 . (13 – 3)

   = 45 . 10

   = 450

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2. Lời giải:

    a ) $35 . 18 – 5 . 7 . 28$

   $= 35 . 18 – 35 . 28$

   $= 35 . ( 18 – 28 )$

   $= 35 . ( -10 )$

   $= -350.$

    b ) $24 . ( 16 – 5 ) + 16 . ( 24 – 5 )$

   $= 24 . 16 – 24 . 5 – 16 . 24 + 16 . 5$

   $= ( 24 . 16 – 16 . 24 ) + ( 16 . 5 – 24 . 5 )$

   $= 0 + 5 . ( 16- 24 )$

   $= 5 . ( -8 )$

   $= -40.$

    c ) $31 . ( -18 ) + 31 . ( -81) – 31$

   $= 31 . (-18) + 31 . (-81) + 31 . (-1)$

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

   $= 31 . ( -100 )$

   $= -3100.$

    d ) $13 . ( 23 + 22 ) – 3 . ( 17 + 28 )$

   $= 13 . 45 – 3 . 45$

   $= 45 . (13 – 3)$

   $= 45 . 10$

   $= 450.$

   Học tốt !!!

   $—Pikachu—$

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