Question

ПОМОГИТЕ ПЛИЗЗ!!!!!!!!!!

Answer 1

$1)(3-\frac{1}{5}a)(3+\frac{1}{5}a)=3^{2}-(\frac{1}{5}a)^{2}=9-\frac{1}{25}a^{2}=9-0,04a^{2}\\\\2)(5b^{2}+1)(1-5b^{2})=1^{2}-(5b^{2})^{2}=1-25b^{4}$