1). 14-14m^2=14(1-m^2)=14(1-m)(1+m); 2).7x-7xy^2=7x(1-y^2)=7x(1-y)(1+y);3). 3x^2-24xy+48y^2=3(x^2-8xy+16y^2)=3(x-4y)^2;4). a^2-2ab+b^2-25=(a-b)^2-5^2=(a-b-5)(a-b+5); 6)7x^3-63x=0, 7x(x^2-9)=0, 7x=0, x1=0; x^2-9=0,(x-3)(x+3)=0, x-3=0, x2=3; x+3=0, x3=-3. Ответ: x1=0, x2=3, x3=-3.