Question

x2y2+2xy-1, 4xy+5 and -9x2y2-10xy -3

Answer 1

(x2y2-2xy+1)+(x2-2xy+y2)=0

(xy-1)2+(xy)2=0

(xy-1)2=0

xy-1=0

xy=1

(xy)2 =0

xy=0

x=y

so when x=1, y=1 ,when x=-1, y=-1