(2x-3)x(3x+2)-(2x-5)x(5x+2) (3x-7)^2-(7x-3)^2

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1. Đáp án:

   `(2x-3)(3x+2)-(2x-5)(5x+2)`

   `=6x²+4x-9x-6-(10x²+4x-25x-10)`

   `=6x²+4x-9x-6-10x²-4x+25x+10`

   `=-4x²+16x+6`

   `(3x-7)^2-(7x-3)^2`

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

   `=(10x-10)(4x-4)`

   @Star

    

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2. Đáp án:

   Ta có : 

   `(2x – 3)(3x + 2) – (2x – 5)(5x + 2)`

   ` = 6x^2 – 9x + 4x – 6 – 10x^2 + 25x – 4x + 10`

   ` = -4x^2 + 16x + 4` 

   `(3x – 7)^2 – (7x – 3)^2`

   ` = (3x – 7 – 7x + 3)(3x – 7 + 7x – 3)`

   ` = (-4x – 4)(10x – 10)`

   ` = -4.(x + 1).10.(x – 1)`

   ` = -40.(x + 1)(x – 1)`

   ` = -40.(x^2 – 1)`

   ` = -40x^2 + 40`

   Giải thích các bước giải:

    

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