\[\boxed{\text{22\ (22).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[\textbf{а)}\ x = 1,2;\ \ \ \ y = - 2,5:\]
\[x\ + \ y\ = \ 1,2\ + \ ( - 2,5) =\]
\[= - (2,5 - 1,2) = \ - 1,3\]
\[xy\ = \ 1,2\ \cdot \ ( - 2,5)\ = \ - 3.\]
\[\textbf{б)}\ x = - 0,8;\ \ \ y = 3:\]
\[\ x\ + \ y\ = \ - 0,8\ + \ 3\ =\]
\[= (3 - 0,8) = \ 2,2\]
\[xy\ = \ - 0,8\ \cdot \ 3\ = \ - 2,4.\]
\[\textbf{в)}\ x = 0,1;\ \ \ \ \ \ y = 0,2:\]
\[\ x\ + \ y\ = \ 0,1\ + \ 0,2\ = \ 0,3\]
\[xy\ = \ 0,1\ \cdot \ 0,2\ = \ 0,02.\]
\[\textbf{г)}\ x = - 1,4;\ \ \ \ \ y = - 1,6:\]
\[x\ + \ y\ = \ - 1,4\ + \ ( - 1,6) =\]
\[= - (1,4 + 1,6) = \ - 3\]
\[xy\ = \ - 1,4\ \cdot \ ( - 1,6)\ = \ 2,24.\ \]