若X+Y=0,XY=11,求X^2-XY+Y^2的值.

若X+Y=0,XY=11,求X^2-XY+Y^2的值.
若X+Y=0,XY=11,求X^2-XY+Y^2的值.

若X+Y=0,XY=11,求X^2-XY+Y^2的值.
X^2-XY+Y^2
=(X+Y)^2-3XY
因为：X+Y=0,XY=11
所以：=0-3*11
=-33

X^2-XY+Y^2=(X+Y)^2-3XY=-33

-33

X^2-XY+Y^2＝ （x+y）^2 - 3xy
=0-11*3
=-33
这类题的一般思路就是把问题里的等式努力往题目中给出的已知条件靠．通过加减乘除等方法变形

=（X+Y）^2-3XY
=-33

X^2-XY+Y^2
=(X+Y)^2-3XY
=0-33
=-33

X^2-XY+Y^2=-33

X^2-XY+Y^2=X^2+2XY+Y^2-3XY
=(X+Y)^2-3XY
=0-33
=-33