First simplify, then evaluate: - (square of X + square of Y) + [- 3xy - (square of X - square of Y)], where x = - 1, y = 2

First simplify, then evaluate: - (square of X + square of Y) + [- 3xy - (square of X - square of Y)], where x = - 1, y = 2

-(square of X + square of Y) + [- 3xy - (square of X - square of Y)]
=-x²-y²-3xy-x²+y²
=-2x²-3xy
When x = - 1, y = 2, the original formula = - 2 * (- 1) & # - 3 * (- 1) * 2 = - 2 + 6 = 4