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

Toán Lớp 8: bài 1 : tìm x : d, x^2-13x -12 e, x^3+4x^2-29x+24 g, x^3+3x^2 +6x +4

Toán Lớp 8: bài 1 : tìm x :
d, x^2-13x -12
e, x^3+4x^2-29x+24
g, x^3+3x^2 +6x +4

Comments ( 1 )

  1. d)x^2-13x-12
    =x^2-12x-x-12
    =(x^2-x)-(12x+12)
    =x(x-1)-12(x+1)
    Sửa đề: x^2+13x+12
    =x^2+12x+x+12
    =(x^2+x)+(12x+12)
    =x(x+1)+12(x+1)
    =(x+1)(x+12)
    e)x^3+4x^2-29x+24
    =x^3-x^2+5x^2-5x-24x+24
    =(x^3-x^2)+(5x^2-5x)-(24x-24)
    =x^2(x-1)+5x(x-1)-24(x-1)
    =(x-1)(x^2+5x-24)
    =(x-1)(x^2+8x-3x-24)
    =(x-1)[(x^2+8x)-(3x+24)]
    =(x-1)[x(x+8)-3(x+8)]
    =(x-1)(x-3)(x+8)
    g)x^3+3x^2+6x+4
    =x^3+2x^2+x^2+2x+4x+4
    =(x^3+2x^2+4x)+(x^2+2x+4)
    =x(x^2+2x+4)+(x^2+2x+4)
    =(x+1)(x^2+2x+4)

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