1、
=(x²+y²)²-(2xy)²
=(x²+2xy+y²)(x²-2xy+y²)
=(x+y)²(x-y)²
2、
=1001²-2×1001×101+101²
=(1001-101)²
=900²
=810000
3、
=99²+2×99+1
=(99+1)²
=100²
=10000
4、
=66²-2×65×66+65²
=(66-65)²
=1²
=1
1、
=(x²+y²)²-(2xy)²
=(x²+2xy+y²)(x²-2xy+y²)
=(x+y)²(x-y)²
2、
=1001²-2×1001×101+101²
=(1001-101)²
=900²
=810000
3、
=99²+2×99+1
=(99+1)²
=100²
=10000
4、
=66²-2×65×66+65²
=(66-65)²
=1²
=1