TÍNH NHANH A. 3/7 x 5/6 + 5/6 x 4/7 B. 4/9 x 5/6 – 1/3 x 4/9 C. 1/6 : 4/5 + 1/8 : 4/5 D. 1/6 : 4/5 – 1/8 : 4/5 (làm cả bước trung gian hộ mình nha,

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1. a) 3/7 x 5/6 + 5/6 x 4/7

   = 5/6 x ( 3/7 + 4/7 )

   = 5/6 x 1

   = 5/6

   b) 4/9 x 5/6 + 1/3 x 4/9

   = 4/9 x ( 5/6 – 1/3 )

   = 4/9 x ( 5/6 – 2/6 )

   = 4/9 x 3/6

   =2/9

   c) 1/6 : 4/5 + 1/8 : 4/5

   = ( 1/6 + 1/8 ) : 4/5

   = ( 4/24 + 3/24 ) x 5/4

   = 7/24 x 5/4

   = 35/96

   d) 1/6 : 4/5 – 1/8 : 4/5

   = ( 1/6 – 1/8 ) : 4/5

   = ( 4/24 – 3/24) x 5/4

   = 1/24 x 5/4

   = 5/96

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2. Đáp án:

   `A = 5/6`

   `B = 2/9`

   `C = 35/96`

   `D = 5/96`

   Giải thích các bước giải:

   `A = 3/7 × 5/6 + 5/6 × 4/7`

   `A = 5/6 × (3/7 + 4/7)`

   `A = 5/6 × 1`

   `A = 5/6`

   `B = 4/9 × 5/6 – 1/3 × 4/9`

   `B = 4/9 × (5/6 – 1/3)`

   `B = 4/9 × 1/2`

   `B = 2/9`

   `C = 1/6 ÷ 4/5 + 1/8 ÷ 4/5`

   `C = 1/6 × 5/4 + 1/8 × 5/4`

   `C = 5/4 × (1/6 + 1/8)`

   `C = 5/4 × 7/24`

   `C = 35/96`

   `D = 1/6 ÷ 4/5 – 1/8 ÷ 4/5`

   `D = 1/6 × 5/4 – 1/8 × 5/4`

   `D = 5/4 × (1/6 – 1/8)`

   `D = 5/4 × 1/24`

   `D = 5/96`

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