计算：-23xy-[2x2+12y2-2(x2-xy+y2)]．

题型：解答题难度：一般来源：不详

计算：-

2

3

xy-[2x2+

1

2

y2-2(x2-xy+y2)]．

答案

原式=-

2

3

xy-2x²-

1

2

y²+2x²-2xy+2y²
=-

8

3

xy+

3

2

y²．