(1)向量OP+PG=OQ+QG=OG=(OA+OB)/3,
PG=(1/3-x)OA+(1/3)OB,
QG=(1/3)OA+(1/3-y)OB,
向量PG‖QG,
∴1/(1-3x)=1-3y,
∴y=(1/3)[1-1/(1-3x)]=x/(3x-1)
由0
(1)向量OP+PG=OQ+QG=OG=(OA+OB)/3,
PG=(1/3-x)OA+(1/3)OB,
QG=(1/3)OA+(1/3-y)OB,
向量PG‖QG,
∴1/(1-3x)=1-3y,
∴y=(1/3)[1-1/(1-3x)]=x/(3x-1)
由0