3. -5/9 . ( 3/10 – 2/5 ) 9. 1/5 – [ 7/8 – (3/4 – 5/2) ] 8. -2/3 – (-2/5) – 7/10 13. –(2/5 – 3/4) – (3/4 + 3/5) 16. (-5/4) : 2 3/5 + 13/4 : 2 3/5 Giúp

0 bình luận về “3. -5/9 . ( 3/10 – 2/5 ) 9. 1/5 – [ 7/8 – (3/4 – 5/2) ] 8. -2/3 – (-2/5) – 7/10 13. –(2/5 – 3/4) – (3/4 + 3/5) 16. (-5/4) : 2 3/5 + 13/4 : 2 3/5 Giúp”

1. 3. $\frac{-5}{9}$ . ($\frac{3}{10}$ – $\frac{2}{5}$)

   = $\frac{-5}{9}$ . $\frac{-1}{10}$

   = $\frac{5}{90}$

   = $\frac{1}{18}$

    

   9. $\frac{1}{5}$ – [$\frac{7}{8}$ – ($\frac{3}{4}$ – $\frac{5}{2}$)]

   Cách 1:

   = 1/5 – [7/8 – (3/4 – 10/4)]

   = 1/5 – [ 7/8 – (-7/4)]

   = 1/5 – (7/8 + 7/4)

   = 1/5 – 21/8

   = 8/40 – 105/40

   = -97/40

   Cách 2:

   = 1/5 – (7/8 – 3/4 + 5/2)

   = 1/5 – (7/8 – 6/8 + 20/8)

   = 1/5 – 21/8

   = -97/40

    

   8. -2/3 – (-2/5) – 7/10

   = -2/3 + 2/5 – 7/10

   = -20/30 + 12/30 – 21/30

   = -8/30 – 21/30

   = -29/30

    

   13. –(2/5 – 3/4) – (3/4 + 3/5)

   = -2/5 + 3/4 – 3/4 – 3/5

   = -2/5 – 3/5

   = -5/5 = -1

    

   16. (-5/4) : 2 3/5 + 13/4 : 2 3/5

   =  -5/4 : 13/5 + 13/4 : 13/5

   = -5/4 . 5/13 + 13/4 . 5/13

   = 5/13 . ( -5/4 + 13/4)

   = 5/13 . 8/4

   = 10/13

    -HỌC TỐT-

   Làm vội:vvv

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2. Đáp án: bên dưới nhek:v

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