Разложить на множители p^2-2pq+q^2-25 49-x^2+2xy-y^2 16x^4y^4-x^4+2x^2y^2-y^4

(p-q)^2-25=(p-q-5)(p-q+5)
49-x^2+2xy-y^2=7^2-(x^2-2xy+y^2)=7^2-(x-y)^2=(7-x+y)(7+x-y)
16x^4y^4-x^4+2x^2y^2-y^4=(4x^2y^2)^2-(x^4-2x^2y^2+y^4)=(4x^2y^2)^2-(x^2-y^2)^2=
(4x^2y^2-x^2+y^2)(4x^2y^2+x^2-y^2)