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

Toán Lớp 8: cm đẳng thức :m^3+n^3+p^3-3mnp=(m+n+p)(m^2+n^2+p^2-mn-np-mp)

Toán Lớp 8: cm đẳng thức :m^3+n^3+p^3-3mnp=(m+n+p)(m^2+n^2+p^2-mn-np-mp)

Comments ( 1 )

  1. VT=m^3+n^3+p^3-3mnp
    =(m^3+3m^2n+3mn^2+n^3)+p^3-3mnp-3m^2n-3mn^2
    =(m+n)^3+p^3-3mn(p+m+n)
    =(m+n+p)[(m+n)^2-(m+n)*p+p^2]-3mn(p+m+n)
    =(m+n+p)(m^2+2mn+n^2-mp-np+p^2-3mn)
    =(m+n+p)(m^2+n^2+p^2-mn-np-mp)=VP
    ->text(đpcm)
    ———–
    áp dụng hđt 
    ***(a+b)^3=a^3+3a^2b+3ab^2+b^3
    ***a^3+b^3=(a+b)(a^2-b+b^2)

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

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