1,tính. a,38×67+33×38 b, 49+785+51 c, 87×134-34×87 d, 5/4×1/3+2/3×5/4 e, 7/2×5/3-2/3×7/2 f, 4×89×25

0 bình luận về “1,tính. a,38×67+33×38 b, 49+785+51 c, 87×134-34×87 d, 5/4×1/3+2/3×5/4 e, 7/2×5/3-2/3×7/2 f, 4×89×25”

1. Đáp án:

   Bài 1: tính

   a) 38 x 67 + 33 x 38

   = 38 x (67 + 33)

   = 38 x 100

   = 3800

   b) 49 + 785 + 51

   = (49 + 51) + 785

   = 100 + 785

   = 885

   c) 87 x 134 – 34 x 87

   = 87 x (134 – 34)

   = 87 x 100

   = 8700

   d) $\dfrac{5}{4}$ x $\dfrac{1}{3}$ + $\dfrac{2}{3}$ x $\dfrac{5}{4}$ 

   = $\dfrac{5}{4}$ x $(\dfrac{1}{3}$ + $\dfrac{2}{3})$

   = $\dfrac{5}{4}$ x $\dfrac{3}{3}$

   = $\dfrac{5}{4}$ x 1

   = $\dfrac{5}{4}$

   e) $\dfrac{7}{2}$ x $\dfrac{5}{3}$ – $\dfrac{2}{3}$ x $\dfrac{7}{2}$ 

   = $\dfrac{7}{2}$ x $(\dfrac{5}{3}$ – $\dfrac{2}{3})$

   = $\dfrac{7}{2}$ x $\dfrac{3}{3}$

   = $\dfrac{7}{2}$

   f) 4 x 89 x 25

   = (4 x 25) x 89

   = 100 x 89

   = 8900

   @Yết gửi bạn nhé~~

   HỌC TỐT~~

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   #NOTHINGISIMPOSSIBLE

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2. a) $38. 67+33.38$
   $=38(67+33)$
   $=38.100=3800$
   b) $49+785+51$

   $=(49+51)+785$

   $=100+785=885$
   c) $87.134-34.87$

   $=87(134-34)$

   $=87.100=8700$

   d) `5/4. 1/3+ 2/3. 5/4`

   `=5/4.(1/3+2/3)`

   `=5/4. 1=5/4`

   e) `7/2. 5/3- 2/3. 7/2`

   `=7/2(5/3-2/3)`

   `=7/2.1=7/2`

   f) $4.89.25$

   $=(4.25).89$

   $=100.89=8900$

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