已知X-Y=2,X^2Y^2=4(1)XY的值(2)X^2008+X^2009的值

已知X-Y=2,X^2Y^2=4(1)XY的值(2)X^2008+X^2009的值

由X^2Y^2=4可得XY=正負2在有X-Y=2的(X-Y)^2=4=X^2+Y^2-2XY可得XY=2因為XY=-2時X=0,Y=0要舍去當XY=2時(X+Y)^2=12,x+y=正負2根號3帶入解得x=根號3+1,y=1-根號3或(x=負根號3+1,y=-根號3-1)所以問題2=……化簡