① -0.01p^2+4q^2
=4q^2-0.01p^2
=4q^2-1/100p^2
=(2q+1/10p)(2q-1/10p)
②(3x-y)^2-(x+3y)^2
=[(3x-y)+(x+3y)][(3x-y)-(x+3y)]
=(3x-y+x+3y)(3x-y-x-3y)
=(4x+2y)(2x-4y)
=4(2x+y)(x-2y)
③ a^4-16b^4
=(a^2+4b^2)(a^2-4b^2)
=(a^2+4b^2)(a+2b)(a-2b)
④(m+n)^2-n^2
=[(m+n)+n][(m+n)-n]
=m(m+2n)
④(m-n)^2-n^2
=[(m-n)+n][(m-n)-n]
=m(m-2n)