1.-(2a-b)^2+49(a-b)^2
=(7a-7b+2a-b)(7a-7b-2a+b)
=(9a-8b)(5a-6b)
2.x^(6n+2)+2x^(3n+2)+x^2
=x^2(x^6n+2x^3n+1)
=x^2(x^3n+1)^2
=x^2(x^n+1)^2(x^2n-x^n+1)^2