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

Toán Lớp 9: Chia đa thức : x^8+x^4+1 chia hết cho x^2+x+1

Toán Lớp 9: Chia đa thức : x^8+x^4+1 chia hết cho x^2+x+1

Comments ( 2 )

  1. Ta có :
    x^8 + x^4 + 1
    =  (x^8 + x^7 + x^6) – (x^7 + x^6 + x^5)  + (x^5 + x^4 + x^3) – (x^3 + x^2 +x) + (x^2 + x +1)
    =  x^6 (x^2 + x  +1) – x^5 (x^2 + x  +1) + x^3 (x^2 + x + 1) – x (x^2 + x  +1) + (x^2 + x+1)
    =  (x^6 – x^5 + x^3 – x +1)(x^2 + x + 1)
    = (x^6 – x^5 + x^3 – x + 1)(x^2 + x +1)
    => x^8 + x^4 + 1 \vdots x^2 + x + 1

  2. \qquad (x^8+x^4+1):(x^2+x+1)
    =(x^8-x^2+x^4-x+x^2+x+1):(x^2+x+1)
    =[x^2(x^6-1)+x(x^3-1)+(x^2+x+1)]:(x^2+x+1)
    =[x^2(x^3-1)(x^3+1)+x(x-1)(x^2+x+1)+(x^2+x+1)]:(x^2+x+1)
    =[(x-1)(x^2+x+1)(x^5+x^2)+(x^2+x+1)(x^2-x)+(x^2+x+1)]:(x^2+x+1)
    =(x^2+x+1)[(x-1)(x^5+x^2)+x^2-x+1]:(x^2+x+1)
    =x^6+x^3-x^5-x^2+x^2-x+1
    =x^6-x^5+x^3-x+1

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