a(3/15-x)*1/3=2/5 b 3/5*x-1/3=1/4 c 1/4+3/4:x=-2 d 3/4+2(2x-2/3)=2

2 bình luận về “a(3/15-x)*1/3=2/5 b 3/5*x-1/3=1/4 c 1/4+3/4:x=-2 d 3/4+2(2x-2/3)=2”

1. Giải đáp:

    

   Lời giải và giải thích chi tiết:

   a)(3/15-x)*1/3=2/5

   1/15-1/3x=2/5                 (1/3*3/15=3/45=1/15)

   -1/3x=2/5-1/15

   -1/3x=1/3                        (2/5-1/15=(6-1)/15=1/3)

   x=-1

   b)3/5x-1/3=1/4      

   3/5x=1/4+1/3

   3/5x=7/12                        (1/4+1/3=(3+4)/12)

   x=7/12 : 3/5

   x=7/12 xx 5/3

   x=35/36

   c) 1/4+3/4 : x =-2

   3/4:x=-2-1/4

   3/4:x=-2,25

   x=-2,25xx3/4

   x=-27/16 = -1,6875

   d) 3/4+2(2x-2/3)=2

   3/4+4x-4/3=2

   4x=2-3/4+4/3

   4x=31/12                         2-3/4+4/3=(24-9+16)/12

   x=31/48                          31/12:4= 31/12xx1/4

   Trả lời
2. a) ( $\frac{3}{15}$ – x ) . $\frac{2}{5}$ =$\frac{2}{5}$ 

       $\frac{3}{15}$ – x   =$\frac{2}{5}$ : $\frac{2}{5}$

       $\frac{3}{15}$ – x   =$\frac{2}{5}$ . $\frac{5}{2}$

       $\frac{3}{15}$ – x   = 1

       x = $\frac{3}{15}$ – 1

       x = $\frac{-4}{5}$

   Vậy x = x = $\frac{-4}{5}$

   b) $\frac{3}{5}$ . x – $\frac{1}{3}$ = $\frac{1}{4}$ 

       $\frac{3}{5}$ . x = $\frac{1}{4}$ + $\frac{1}{3}$ 

       $\frac{3}{5}$ . x = $\frac{3}{12}$ + $\frac{4}{12}$ 

       $\frac{3}{5}$ . x = $\frac{7}{12}$

       x = $\frac{7}{12}$ : $\frac{3}{5}$

       x = $\frac{7}{12}$ . $\frac{5}{3}$

       x = $\frac{35}{36}$

   Vậy x = $\frac{35}{36}$

   c ) $\frac{1}{4}$ + $\frac{3}{4}$ : x = -2

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

        $\frac{3}{4}$ : x = $\frac{-8}{4}$ – $\frac{1}{4}$

        $\frac{3}{4}$ : x = $\frac{-9}{4}$

        x = $\frac{3}{4}$ : $\frac{-9}{4}$

        x = $\frac{3}{4}$ . $\frac{4}{-9}$

        x = $\frac{1}{-3}$

   Vậy x = $\frac{1}{-3}$

   d) $\frac{3}{4}$ + 2(2x – $\frac{2}{3}$ ) = 2

        2(2x – $\frac{2}{3}$ ) = 2 – $\frac{3}{4}$

        2(2x – $\frac{2}{3}$ ) = $\frac{8}{4}$ – $\frac{3}{4}$

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

        2x – $\frac{2}{3}$  = $\frac{5}{4}$ : 2

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

        2x – $\frac{2}{3}$  = $\frac{5}{8}$

        2x = $\frac{5}{8}$ + $\frac{2}{3}$

        2x = $\frac{15}{24}$ + $\frac{16}{24}$

        2x = $\frac{31}{24}$

        x = $\frac{31}{24}$ : 2

        x = $\frac{31}{48}$

   Vậy x = $\frac{31}{48}$

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   Trả lời