若a+b+c=0,1a+1+1b+2+1c+3=0,那么(a+1)2+(b+2)2+(c+3)2=______.

3个回答

  • 解题思路:由a+b+c=0得,(a+1)+(b+2)+(c+3)=6,两边平方得(a+1)2+(b+2)2+(c+3)2+2(a+1)(b+2)+2(a+1)(c+3)+2(b+2)(c+3)=36,再由

    1

    a+1

    +

    1

    b+2

    +

    1

    c+3

    =0

    去分母,得(b+2)(c+3)+(a+1)(c+3)+(a+1)(b+2)=0,代入上式即可.

    ∵a+b+c=0,

    ∴(a+1)+(b+2)+(c+3)=6,

    两边平方得(a+1)2+(b+2)2+(c+3)2+2[(a+1)(b+2)+(a+1)(c+3)+(b+2)(c+3)]=36,

    又由

    1

    a+1+

    1

    b+2+

    1

    c+3=0去分母,得

    (b+2)(c+3)+(a+1)(c+3)+(a+1)(b+2)=0,

    ∴(a+1)2+(b+2)2+(c+3)2=36.

    故答案为:36.

    点评:

    本题考点: 分式的混合运算.

    考点点评: 本题考查了分式的混合运算.关键是将已知等式变形,得出与所求结果相同的结构,采用两边平方的方法求解.