Question

помогите пожалуйста......

Answer 1

1)(x+0,6)(x-0,6)=x^2-9/25;
2)9m^2-100n^2=3^2m^2-10^2n^2=(3m)^2-(10n)^2=(3m-10n)(3m+10n);
3)0,49x^2-169y^2=49/100x^2-169y^2=(7/10x-13y)(7/10x+13y);
4)(x+9y)(x-9y)=x^2-9y^2=x^2-81y^2.