a. -5/7×2/11+ -5/7×9/11+12/7 b.-4/5×1/2+ -4/5×1/3- -4/5÷1/4 c.1/4+3/4×(-1/2+2/3 d.2/5-3/4-1/2 e.7/2- 50/100 f.8/15× -9/14+8/15× -5/14 g.-3/7+5/13+ -4/

0 bình luận về “a. -5/7×2/11+ -5/7×9/11+12/7 b.-4/5×1/2+ -4/5×1/3- -4/5÷1/4 c.1/4+3/4×(-1/2+2/3 d.2/5-3/4-1/2 e.7/2- 50/100 f.8/15× -9/14+8/15× -5/14 g.-3/7+5/13+ -4/”

1. a. `-5/7 × 2/11 + -5/7 × 9/11 + 12/7`

   `= -5/7 . ( 2/11 + 9/11 ) + 12/7`

   `= -5/7 . 1 + 12/7`

   `= -5/7 + 12/7`

   `= 7/7 = 1`

   b. `-4/5 × 1/2 + -4/5 × 1/3- (-4/5) : 1/4`

   `= -4/5 × 1/2 + -4/5 × 1/3 + 4/5 : 1/4`

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

   `= -4/5 . ( 6/12 + 4/12 : 3/12 )`

   `= -4/5 . ( 6/12 + 4/12 . 12/3 )`

   `= -4/5 . ( 6/12 + 4/3 )`

   `= -4/5 . ( 6/12 + 16/12 )`

   `= -4/5 . 22/12`

   `= -4/5 . 11/6`

   `= -44/30`

   `= -22/15`

   c. `1/4 + 3/4 × ( -1/2 + 2/3 )`

   `= 1/4 + 3/4 . ( -3/6 + 4/6 )`

   `= 1/4 + 3/4 . 1/4`

   `= 1/4 + 3/16`

   `= 4/16 + 3/16`

   `= 7/16`

   d. `2/5 – 3/4 – 1/2`

   `= 4/20 – 15/20 – 10/20`

   `= -21/10`

   e. `7/2 – 50/100`

   `= 350/100 – 50/100`

   `= 300/100`

   `= 3/1 = 3`

   f. `8/15 × -9/14 + 8/15 × -5/14`

   `= 8/15 . ( -9/14 + -5/14 )`

   `= 8/15 . ( -1 )`

   `= -8/15`

   g.` -3/7 + 5/13 + -4/7`

   `= ( -3/7 + -4/7 ) + 5/13`

   `= -1 + 5/13`

   `= -13/13 + 5/13`

   `= -8/13`

   h. `146/13 – (18/7 + 68/13)`

   `= 146/13 – 18/7 – 68/13`

   `= ( 146/13 – 68/13 ) – 18/7`

   `= 78/13 – 18/7`

   `= 546/91 – 234/91`

   `= 312/91`

    

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2. a, $\frac{-5}{7}$ x $\frac{2}{11}$ + $\frac{-5}{7}$ x $\frac{9}{11}$ + $\frac{12}{7}$

   = $\frac{-5}{7}$ x ($\frac{2}{11}$ + $\frac{9}{11}$) + $\frac{12}{7}$

   = $\frac{-5}{7}$ x 1 + $\frac{12}{7}$

   = $\frac{-5}{7}$ + $\frac{12}{7}$

   = $\frac{7}{7}$

   = 1

   b, $\frac{-4}{5}$ x $\frac{1}{2}$ + $\frac{-4}{5}$ x $\frac{1}{3}$ – $\frac{-4}{5}$ : $\frac{1}{4}$

   = $\frac{-4}{5}$ x $\frac{1}{2}$ + $\frac{-4}{5}$ x $\frac{1}{3}$ – $\frac{-4}{5}$ x 4

   = $\frac{-4}{5}$ x ($\frac{1}{2}$ + $\frac{1}{3}$ – 4)

   = $\frac{-4}{5}$ x $\frac{-19}{6}$

   = $\frac{38}{15}$

   c, $\frac{1}{4}$ + $\frac{3}{4}$ x (-$\frac{1}{2}$ + $\frac{2}{3}$)

   = $\frac{1}{4}$ + $\frac{3}{4}$ x ($\frac{-3}{6}$ + $\frac{4}{6}$)

   = $\frac{1}{4}$ + $\frac{3}{4}$ x $\frac{1}{6}$

   = $\frac{1}{4}$ + $\frac{1}{8}$

   = $\frac{2}{8}$ + $\frac{1}{8}$

   = $\frac{3}{8}$

   d, $\frac{2}{5}$ – $\frac{3}{4}$ – $\frac{1}{2}$

   = $\frac{8}{20}$ – $\frac{15}{20}$ – $\frac{10}{20}$

   = -$\frac{17}{20}$

   e, $\frac{7}{2}$ – $\frac{50}{100}$

   = $\frac{7}{2}$ – $\frac{1}{2}$

   = $\frac{6}{2}$

   = 3

   f, $\frac{8}{15}$ x $\frac{-9}{14}$ + $\frac{8}{15}$ x $\frac{-5}{14}$

   = $\frac{8}{15}$ x ($\frac{-9}{14}$ – $\frac{5}{14}$)

   = $\frac{8}{15}$ x (-1)

   = -$\frac{8}{15}$

   g, $\frac{-3}{7}$ + $\frac{5}{13}$ – $\frac{4}{7}$

   = ($\frac{-3}{7}$ – $\frac{4}{7}$) + $\frac{5}{13}$

   = -1 + $\frac{5}{13}$

   = -1$\frac{5}{13}$

   = $\frac{-8}{13}$

   h, $\frac{146}{13}$ – ($\frac{18}{7}$ + $\frac{68}{13}$)

   = $\frac{146}{13}$ – $\frac{18}{7}$ – $\frac{68}{13}$

   = ($\frac{146}{13}$ – $\frac{68}{13}$) – $\frac{18}{7}$

   = 6 – $\frac{18}{7}$

   = $\frac{42}{7}$ – $\frac{18}{7}$

   = $\frac{24}{7}$

   (Cho mk ctlhn nha, thanks ^.^

   Chúc bạn học tốt !!!)

    

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