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

Toán Lớp 8: cho x+y+z=0 và x^2+y^2+z^2=0 tính B=x^4+y^4+z^4

Toán Lớp 8: cho x+y+z=0 và x^2+y^2+z^2=0
tính B=x^4+y^4+z^4

Comments ( 1 )

  1. $\\$
    x+y+z=0
    <=>x^2+y^2+z^2+2(xy+yz+xz)=0
    <=> 2 (xy+yz+xz)=0
    <=> xy + yz +xz=0
    <=> (xy+yz+xz)^2=0
    <=> x^2y^2+y^2z^2+x^2z^2=0
    x^2+y^2+z^2=0
    <=>(x^2+y^2+z^2)^2=0
    <=>x^4+y^4+z^4+2(x^2y^2+y^2z^2+z^2x^2)=0
    <=>x^4+y^4+z^4 = 0
    <=>B=0
    Vậy B=0

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