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

Toán Lớp 8: Pt thành n tử a) x^3 -19x -30 b) x^4 +x^2 +1

Tháng Một 18, 2023 Toán học 1 Comment 0 views

Toán Lớp 8: Pt thành n tử
a) x^3 -19x -30
b) x^4 +x^2 +1

Comments ( 1 )

  1. phuongthuydung
    phuongthuydung
    18 Tháng Một, 2023 at 2:33 sáng
    Reply
    ~rai~
    \(a)x^3-19x-30\\=x^3-5x^2+5x^2-25x+6x-30\\=(x^3-5x^2)+(5x^2-25x)+(6x-30)\\=x^2(x-5)+5x(x-5)+6(x-5)\\=(x-5)(x^2+5x+6)\\=(x-5)(x^2+2x+3x+6)\\=(x-5)[(x^2+2x)+(3x+6)]\\=(x-5)[x(x+2)+3(x+2)]\\=(x-5)(x+2)(x+3).\\b)x^4+x^2+1\\=x^4+x^3-x^3+x^2+1\\=(x^4+x^3+x^2)-(x^3-1)\\=x^2(x^2+x+1)-(x-1)(x^2+x+1)\\=(x^2+x+1)[x^2-(x-1)]\\=(x^2+x+1)(x^2-x+1).\)

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

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