1) 2x^2 - 14xy - 14xy + 98y^2 = 2x(x - 7y) - 14y(x - 7y) = (2x - 14y)(x - 7y) = 2(x - 7y)(x - 7y) = 2(x - 7y)^2
2) -2n^4(9n^4 - 6n^2 + 1) = -2n^4(3n^2 - 1)^2
3) 3(x^3 - 27y^3) = 3(x - 3y)(x^2 + 3xy + 9y^2)
1) 2x^2 - 14xy - 14xy + 98y^2 = 2x(x - 7y) - 14y(x - 7y) = (2x - 14y)(x - 7y) = 2(x - 7y)(x - 7y) = 2(x - 7y)^2
2) -2n^4(9n^4 - 6n^2 + 1) = -2n^4(3n^2 - 1)^2
3) 3(x^3 - 27y^3) = 3(x - 3y)(x^2 + 3xy + 9y^2)