1) Tìm x a) 2/9 – 7/8 . x = 1 b) 4/5 + 7/6 : x = 1/6 c) 5/9 : x – 3 = -2/7 d) 2/5 . x + 1/3 = 1/5 2) Tính giá trị biểu thức a) 3/4 : ( 1/2 : 4/5 ) b)

0 bình luận về “1) Tìm x a) 2/9 – 7/8 . x = 1 b) 4/5 + 7/6 : x = 1/6 c) 5/9 : x – 3 = -2/7 d) 2/5 . x + 1/3 = 1/5 2) Tính giá trị biểu thức a) 3/4 : ( 1/2 : 4/5 ) b)”

1. Bài `1 :`

   `a) 2/9 – 7/8 . x = 1`

   `=> 7/8 . x = -7/9`

   `=> x = -7/9 : 7/8`

   `=> x = -8/9`

   `b) 4/5 + 7/6 : x = 1/6`

   `=> 7/6 : x = -19/30`

   `=> x = 7/6 : -19/30`

   `=> x = 35/-19`

   `c) 5/9 : x – 3 = -2/7`

   `=> 5/9 : x = 19/7`

   `=> x = 5/9 : 19/7`

   `=> x = 35/171`

   `d) 2/5 . x + 1/3 = 1/5`

   `=> 2/5 . x = -2/15`

   `=> x = -2/15 : 2/5`

   `=> x = -1/6`

    Bài `2 :`

   `a) 3/4 : ( 1/2 : 4/5 )`

   `= ( 3/4 : 1/2 ) : 4/5`

   `= 3/2 : 4/5`

   `= 15/8`

   `b) ( 7/12 . 9/14 ) : 1/2`

   `= ( 7/12 : 1/2 ) . 9/14`

   `= 7/6 . 9/14`

   `= 3/4`

   `c) ( 7/12 . 9/14 ) : ( 1/2 . 6/5 )`

   `= \frac{ 7.9}{12.14} : \frac{1.6}{2.5}`

   `= \frac{7.9.2.5}{12.14.1.6}`

   `= 5/48`

   Bài `3 :`

    `\frac{ 3/4 + 3/5 + 3/7 – 3/11}{6/4 + 6/5 + 6/7 – 6/11}`

   `= \frac{ 3( 1/4 + 1/5 + 1/7 – 1/11 )}{ 6( 1/4 + 1/5 + 1/6 – 1/11)}`

   `= 3/6 = 1/2`

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