设k=a+b−cc=a−b+cb=−a+b+ca,则k的值为_.
问题描述:
设k=
=a+b−c c
=a−b+c b
,则k的值为______. −a+b+c a
答
当a+b+c≠0时,∵
=a+b−c c
=a−b+c b
,−a+b+c a
∴
=a+b−c c
=a−b+c b
=−a+b+c a
=k=a+b−c+a−b+c−a+b+c a+b+c
=1a+b+c a+b+c
当a+b+c=0时,即a+b=-c,所以k=
=a+b−c c
=-2−c−c c
所以k的值为1或-2.