1.x²y²-1/4(x²+y²)²
2.(1-x²)(1-y²)-4xy
3.4(x²)²+1
4.x²-x+y²+y-2xy-6
5.(x-1)(x-2)-2(2-x)²
6.(a²+ab+b²)²-9a²b²
7.a²-b²-2a+1
8.x²(x-y)+(y-x)
9.(a²-2ab+b²)-4
10.(a+b09a-b)+4(b-1)
11.a²+2ab+b²-4(a+b)+3
1.x²y²-1/4(x²+y²)²
2.(1-x²)(1-y²)-4xy
3.4(x²)²+1
4.x²-x+y²+y-2xy-6
5.(x-1)(x-2)-2(2-x)²
6.(a²+ab+b²)²-9a²b²
7.a²-b²-2a+1
8.x²(x-y)+(y-x)
9.(a²-2ab+b²)-4
10.(a+b09a-b)+4(b-1)
11.a²+2ab+b²-4(a+b)+3