1.（x+p)^2-(x+y)^2
=(x+p+x+y)(x+p-x-y)
=(2x+p+y)(p-y)
2.36(x+y)^2-49(x-y)^2
=[6(x+y)-7(x-y)][6(x+y)+7(x-y)]
=(-x+13y)(13x-y)
=-(x-13y)(13x-y)
3.(x^2+x+1)^2-1
=(x²+x+2)(x²+x)
=x(x+1)(x²+x+2)