7. Which one of the following is a sketch of the graph $$( x + y ) \left( x ^ { 2 } - x y + y ^ { 2 } \right) = 1 ?$$ [Figure]
7. Which one of the following is a sketch of the graph
$$( x + y ) \left( x ^ { 2 } - x y + y ^ { 2 } \right) = 1 ?$$
\includegraphics[max width=\textwidth, alt={}, center]{a6b2cfbb-8b77-49a4-83f6-79664566060f-07_1221_1243_442_440}\\