1、x²+y²=(x+y)²-2xy=3²-2x(-12)=33 2、x²-xy+y²=(x+y)²-3xy=3²-3x(-12)=45
,①X^2+Y^2=(x+y)²-2xy=3²-2×(-12)=33②X^2-XY+Y^2 =33-(-12)=45
