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

Toán Lớp 8: Tìm x,y,z a, x ² + 3y ² +2z ² – 2x +12y + 4z + 15 = 0

Toán Lớp 8: Tìm x,y,z
a, x ² + 3y ² +2z ² – 2x +12y + 4z + 15 = 0

Comments ( 1 )

  1. a)x ^² + 3y ^² +2z^ ² – 2x +12y + 4z + 15 = 0
    <=> x^2 -2x+1+3y^2+12y+12+2z^2+4z+2=0
    <=>(x+1)^2+3(y^2+4y+4)+2(z^2+2z+1)=0
    <=> (x-1)^2+3(y+2)^2+2(z+1)^2=0
    <=> $\begin{cases} x-1=0\\y+2=0\\z+1=0 \end{cases}$
    <=> $\begin{cases} x=1\\y=-2\\z=-1 \end{cases}$
    @thew
     

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