Question

срочно 25 баллов на фото !!!

Answer 1

$\frac{m}{n}=\frac{1}{2} \ \Rightarrow \ n=2m\\\\\frac{4m^{2}+2mn-n^{2}}{8m^{2}+3n^{2}} =\frac{4m^{2}+2m*2m-(2m)^{2}}{8m^{2}+3*(2m)^{2}}=\frac{4m^{2}+4m^{2}-4m^{2}}{8m^{2}+12m^{2}} =\\\\=\frac{4m^{2} }{20m^{2} }=\frac{1}{5}=\boxed{0,2}$