1)-7.(3x-5)+2(7x-14)=28 2)4.(x-5)-3(x=7)=5.(-4) 3)5(4-x)-7(-x+2)=-4-9+3 4)-3.(x-5)+6(x+2)=9 5)4x-5.(-3+x)=7

0 bình luận về “1)-7.(3x-5)+2(7x-14)=28 2)4.(x-5)-3(x=7)=5.(-4) 3)5(4-x)-7(-x+2)=-4-9+3 4)-3.(x-5)+6(x+2)=9 5)4x-5.(-3+x)=7”

1. `1) `

   ` -7(3x-5) +2(7x-14) = 28`

   ` => -21x +35 +14x -28 = 28`

   ` => -7x + 7 = 28`

   ` => -7x = 21`

   ` => x = -3`

   `2)`

   ` 4(x-5) -3(x+7) = 5*(-4)`

   ` => 4x -20 -3x -21 = -20`

   ` => x – 41 = -20`

   ` => x =-20+41`

   ` => x= 21`

   `3)`

   `5(4-x) – 7(-x+2) = -4-9+3`

   ` => 20 -5x +7x -14 = -10`

   `=> 2x +6 = -10`

   ` => 2x= -16`

   ` => x= -8`

   `4)`

   ` -3(x-5) +6(x+2) = 9`

   ` => -3x +15 +6x +12 = 9`

   ` => 3x + 27 = 9`

   ` => 3x = -18`

   ` => x=-6`

   `5)`

   ` 4x -5(-3+x) = 7`

   ` => 4x +15 -5x = 7`

   `=> -x +15 = 7`

   ` => -x = -8`

   ` => x=8`

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2. Đáp án:

    

   Giải thích các bước giải:

   1, -7.(3x-5)+2(7x-14)=28

   `->-21x+35+14x-28=28`

   `->-21x+14x=28-35+28`

   `->-7x=21`

   `->x=-3`

   2, 4.(x-5)-3(x+7)=5.(-4)

   `->4x-20-3x-21=-20`

   `->4x-3x=-20+20+21`

   `->x=21`

   3, 5(4-x)-7(-x+2)=-4-9+3

   `->20-5x+7x-14=-10`

   `->-5x+7x=-10-20+14`

   `->2x=-16`

   `->x=-8`

   4, -3.(x-5)+6(x+2)=9

   `->-3x+15+6x+12=9`

   `->-3x+6x=9-15-12`

   `->3x=-18`

   `->x=-6`

   5, 4x-5.(-3+x)=7

   `->4x+15-5x=7`

   `->4x-5x=7-15`

   `->-x=-8`

   `->x=8`

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