Question

Помогите пожалуйста!

Answer 1

$\displaystyle\tt \frac{b}{a}= \frac{1}{2} \ \ \Rightarrow \ \ \boxed{\tt a=2b} \\\\\\ \frac{a^2-2ab+b^2}{a^2+b^2}=\frac{(2b)^2-2\cdot2b\cdot b+b^2}{(2b)^2+b^2}=\frac{4b^2-4b^2+b^2}{4b^2+b^2}=\frac{b^2}{5b^2}=\frac{1}{5}=0.2$