Thực hiện tính nhanh: a) ( $\frac{1}{3}$ + $\frac{12}{67}$ + $\frac{13}{41}$ ) – ( $\frac{79}{67}$ – $\frac{28}{41}$ ) b) $\frac{38}

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1. Đáp án:

   A) $\dfrac{1}{3}$ 

   B) $\dfrac{14}{11}$

   Giải thích các bước giải:

   a)

   $(\dfrac{1}{3} + \dfrac{12}{67} + \dfrac{13}{41}) – (\dfrac{79}{67} – \dfrac{28}{41})$

   $=\dfrac{1}{3} + \dfrac{12}{67} + \dfrac{13}{41} – \dfrac{79}{67} + \dfrac{28}{41}$

   $=(\dfrac{13}{41} + \dfrac{28}{41}) + (\dfrac{12}{67} – \dfrac{79}{67}) + \dfrac{1}{3}$

   $= 1 + (-1) + \dfrac{1}{3}$

   $= 0 + \dfrac{1}{3}$

   $= \dfrac{1}{3}$

   b)

   $\dfrac{38}{45} – (\dfrac{8}{45} – \dfrac{17}{51} – \dfrac{3}{11})$

   $=\dfrac{38}{45} – \dfrac{8}{45} + \dfrac{17}{51} + \dfrac{3}{11}$

   $=\dfrac{30}{45} + (\dfrac{17}{51} – \dfrac{3}{11})$

   $=\dfrac{2}{3} + \dfrac{17}{51} + \dfrac{3}{11}$

   $=\dfrac{34}{51} + \dfrac{17}{51} + \dfrac{3}{11}$

   $= 1 + \dfrac{3}{11}$

   $= \dfrac{14}{11}$

   Trả lời

2. `a ) (1/3 + 12/67 + 13/41 ) – ( 79/67 – 28/41) `

   `= 1/3 + 12/67 + 13/41 – 79/67 + 28/41`

   `= ( 12/67 – 79/67 ) + ( 13/41 + 28/41 ) + 1/3`

   `= -67/67 + 41/41 + 1/3 =  -1 + 1  + 1/3`

   `= 0 + 1/3`

   `= 1/3`

   `b )38/45 – ( 8/45 – 17/51 – 3/11 )`

   `=38/45 – 8/45 + 17/51 + 3/11`

   `= 30/45 + 17/51 + 3/11`

   `= 2/3 + 17/51 + 3/11`

   `= 34/51 + 17/51 + 3/11`

   `= 51/51 + 3/11 = 1 + 3/11`

   `= 14/11`

    

   Trả lời