Question

помогите решить 1, 4

Answer 1

$boxed{a^2-b^2=(a-b)(a+b)}\\displaystylesf frac{38^2-28^2}{47^2-19^2}=frac{(38-28)(38+28)}{(47-19)(47+19)} =frac{10cdot 66}{28cdot 66}=frac{10}{28}=frac{5}{14}\\frac{200^2-380^2}{420^2-160^2} =frac{(200-380)(200+380)}{(420-160)(420+160)}=frac{-180cdot 580}{260cdot 580}=-frac{180}{260}=-frac{9}{13}$

Answer 2

5|4. - 9|4