A=3x^2.(x+1)-2x.(x^2.+3)-x^2.(x+3) B=(3x-1).(2x+5)-(3x+2).(2x+3) C=2.(x+5).(2x+1)-(4x-3).(x+6) D=x.(2x+3).(2x-3)-4x.(x+3).(x-3) RÚT GỌN BIỂU THỨC SẼ Đ

0 bình luận về “A=3x^2.(x+1)-2x.(x^2.+3)-x^2.(x+3) B=(3x-1).(2x+5)-(3x+2).(2x+3) C=2.(x+5).(2x+1)-(4x-3).(x+6) D=x.(2x+3).(2x-3)-4x.(x+3).(x-3) RÚT GỌN BIỂU THỨC SẼ Đ”

1. `a) A = 3x^2 . (x+1) – 2x . (x^2 + 3) – x^2 . (x+3)`

   ` = 3x^3 + 3x^2 – 2x^3 – 6x – x^3 – 3x^2`

   ` = (3x^3 – 2x^3 – x^3) + (3x^2- 3x^2) – 6x`

   ` = 0 + 0 – 6x`

   ` = -6x`

   `b) B=(3x-1).(2x+5)-(3x+2).(2x+3)`

   ` = (6x^2 + 15x – 2x – 5) – (6x^2 + 9x + 4x + 6)`

   ` = 6x^2 + 15x – 2x – 5 – 6x^2 – 9x – 4x – 6`

   ` = (6x^2 – 6x^2) + (15x – 2x – 9x – 4x) – (5+6)`

   ` = -11`

   `c) C=2.(x+5).(2x+1)-(4x-3).(x+6)`

   `= (2x + 10).(2x+1) – (4x^2 + 24x – 3x – 18)`

   ` = 4x^2 + 2x + 20x + 10 – 4x^2 – 24x + 3x + 18`

   ` = (4x^2 – 4x^2) + (2x+ 20x – 24x + 3x)  + (10+18)`

   ` = x + 28`

   `d) D=x.(2x+3).(2x-3)-4x.(x+3).(x-3)`

   ` = (2x^2 + 3x).(2x-3) – 4x.(x^2 – 9)`

   ` = 4x^3 – 6x^2 + 6x^2 – 9x – 4x^3 + 36x`

   ` = (4x^3 – 4x^3) + (6x^2 – 6x^2) + (36x – 9x)`

   ` = 27x`

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2. `a)A=3x^2(x+1)-2x(x^2+3)-x^2(x+3)`

   `=(3x^3+3x^2)-(2x^3+6x)-(x^3+3x^2)`

   `=3x^3+3x^2-2x^3-6x-x^3-3x^2`

   `=(3x^3-2x^3-x^3)+(3x^2-3x^2)-6x`

   `=-6x`

   `b)(3x-1)(2x+5)-(3x+2)(2x+3)`

   `=(6x^2+13x-5)-(6x^2+13x+6)`

   `=6x^2+13x-5-6x^2-13x-6`

   `=(6x^2-6x^2)+(13x-13x)-(5+6)`

   `=-11`

   `c)C=2(x+5)(2x+1)-(4x-3)(x+6)`

   `=(4x^2+22x+10)-(4x^2+21x-18)`

   `=4x^2+22x+10-4x^2-21x+18`

   `=(4x^2-4x^2)+(22x-21x)+(10+18)`

   `=x+28`

   `d)x(2x+3)(2x-3)-4x(x+3)(x-3)`

   `=(4x^3-9x)-(4x^3-36x)`

   `=4x^3-9x-4x^3+36x`

   `=(4x^3-4x^3)+(36x-9x)`

   `=27x`

    

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