若X^2+XY=2,XY—Y^2=-7,则X^2+Y^2=( );X^2+3XY-2Y^2=( )

来源:学生作业帮助网 编辑:六六作业网 时间:2024/12/25 16:58:45
若X^2+XY=2,XY—Y^2=-7,则X^2+Y^2=();X^2+3XY-2Y^2=()若X^2+XY=2,XY—Y^2=-7,则X^2+Y^2=();X^2+3XY-2Y^2=()若X^2+X

若X^2+XY=2,XY—Y^2=-7,则X^2+Y^2=( );X^2+3XY-2Y^2=( )
若X^2+XY=2,XY—Y^2=-7,则X^2+Y^2=( );X^2+3XY-2Y^2=( )

若X^2+XY=2,XY—Y^2=-7,则X^2+Y^2=( );X^2+3XY-2Y^2=( )
-12(2式乘以2再加上1式)

9 (1式减2式)
-12(2式乘以2再加上1式)