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

Toán Lớp 8: 1.(x+y+z)*(x-y-z) 2.(x-y+z)*(x+y+z)

Toán Lớp 8: 1.(x+y+z)*(x-y-z)
2.(x-y+z)*(x+y+z)

Comments ( 2 )

  1. 1.(x+y+z)(x-y-z)
    =x^{2}-xy-xz+xy-y^{2}-yz+xz-yz-z^{2}
    =x^{2}-y^{2}-z^{2}-2zy
    2.(x-y+z)(x+y+z)
    =x^{2}+xy+xz-xy-y^{2}-yz+xz+yz+z^{2}
    =x^{2}-y^{2}+z^{2}+2xz

  2. Giải đáp:
     
    Lời giải và giải thích chi tiết:
    1,  ( x+ y+ z).(x – y – z )
    ⇔ x² – xy – xz +xy -y²-yz + xz – yz -z²
    ⇔x² – y² -z²-2xy
    2,( x-y+ z).(x+y+z)
    ⇔ x²+xy+xz -xy -y² -yz + xz+yz +z²
    ⇔ x² – y² +z² +2xz
    chúc bạn học tốt
     

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

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