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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: giúp mình rút gọn 2 biểu thức này với (x –1)2–(x –3)(x2+ 3x + 9) (3x –1)2+ 2(3x –1)(2x + 5) + (2x + 5)2

Toán Lớp 8: giúp mình rút gọn 2 biểu thức này với
(x –1)2–(x –3)(x2+ 3x + 9)
(3x –1)2+ 2(3x –1)(2x + 5) + (2x + 5)2

Comments ( 2 )

  1. a,
    (x-1)^2-(x-3)(x^2+3x+9)
    =(x^2-2x+1)-(x^3-3^3)
    =x^2-2x+1-x^3-9
    =x^2-x^3-2x-8
    b,
    (3x-1)^2+2(3x-1)(2x+5)+(2x+5)^2
    =(3x-1+2x+5)^2
    =(x+4)^2
    =x^2+2.x.4+4^2
    =x^2+8x+16
     

  2. Câu đầu
    $= x^2 – 2x + 1 – x^3 + 27$
    $= x^2 – 2x + 28-x^3$
    Câu hai:
    $= 9x^2 – 6x + 1 + 12x^2 + 30x -4x – 10 + 4x^2 + 20x + 25$
    $= 25x^2 + 40x + 16$

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222-9+11+12:2*14+14 = ? ( )

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