What is the simplified form of the following expression? Assume x greater-than-or-equal-to 0 and y greater-than-or-equal-to 0 2 (RootIndex 4 StartRoot 16 x EndRoot) minus 2 (RootIndex 4 StartRoot 2 y EndRoot) + 3 (RootIndex 4 StartRoot 81 x EndRoot) minus 4 (RootIndex 4 StartRoot 32 y EndRoot)