1、(x+p)^2-(x+q)^2
=(x+p+x+q)(x+p-x-q)
=(2x+p+q)(p-q)
2、(a+b)^2-1
=(a+b+1)(a+b-1)
3、x-1+b^2(1-x)
=b^2(1-x)-(1-x)
=(b^2-1)(1-x)
=(b+1)(b-1)(1-x)
4、12x^2-3y^2
=3(4x^2 -y^2)
3(2x+y)(2x-y)