Giúp mik nha ;) a, 53 . 39 + 47 . 39 – 53 . 21 – 47 . 21 b, 2 . 53 . 12 + 4 . 6 . 87 – 3 . 8 . 40 c, 5 . 7 . 77 – 7 . 60 + 49 . 25 – 15 . 42

0 bình luận về “Giúp mik nha ;) a, 53 . 39 + 47 . 39 – 53 . 21 – 47 . 21 b, 2 . 53 . 12 + 4 . 6 . 87 – 3 . 8 . 40 c, 5 . 7 . 77 – 7 . 60 + 49 . 25 – 15 . 42”

1. Giải thích các bước giải:

   $a)53.39+47.39-53.21-47.21$

   $=53(39-21)+47(39-21)$

   $=53.18+47.18$

   $=(53+47).18 $

   $=100.18$

   $=1800$

   $b)2.53.12+4.6.87-3.8.40$

   $=2.12.53+24.87-24.40$

   $=24.53+24.87-24.40$

   $=24.(53+87-40)$

   $=24.100$

   $=2400$

   $c)5.7.77-7.60+49.25-15.42$

   $=35.77-7.5.12+7.7.5.5-3.5.7.6$

   $=35.77-35.12+35.35-35.18$

   $=35.(77-12+35-18)$

   $=35.82$

   $=2870$

   Học tốt!!!

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2. `a` , $53.39.47.39-53.21-47.21$

   $=39(53+47)-21(53+47)$

   $=(39-21)(53+47)$

   $=18.100$

   $=1800$ 

   `b` , $2.53.12+4.6.87-3.8.40$

   $=24.53+24.87-24.40$

   $=24(53+87-40)$

   $=24.100$

   $=2400$ 

   `c` , $5.7.77-7.60+49.25-15.42$

   $=5.7.77-5.7.12+5.7.5.7-5.7.3.6$

   $=5.7(77-12+5.7-3.6)$

   $=35(77-12+35-18)$

   $=35.82$

   $=2870$

    

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