467.
1. 25x^2-(x+y)^2=(5x-x-y)*(5x+x+y)=(4x-y)*(6x+y).
2. 1-(a^2+b^2)^2==(1-a^2-b^2)*(1+a^2+b^2).
3. x^4*y^2-(a^2-b^2)^2=(x^2*y-a^2+b^2)*(x^2*y+a^2-b^2).
468.
1. (a+2b)^2-(3c+4d)^2=(a+2b-3c-4d)*(a+2b+3c+4d).
2. (m-2n)^2-(2p-3q)^2=(m-2n-2p+3q)*(m-2n+2p-3q).
3. 9(m+n)^2-(m-n)^2=(3m+3n-m+n)*(3m+3n+m-n)=(2m+4n)*4m+2n).
4. 16(a+b)^2-9(x+y)^2=(4a+4b-3x-3y)*(4a+4b+3x+3y).