(x²y²-4)(-x²y²-4)-4(xy-1/2)·(xy-12),=-[(xy)²-4²]-4(xy-1/2)²=-[(-2)²-4²]-4(-2-1/2)²=-(4-16)-4*(5/2)²=12-4*25/4=12-25=-13
先化简,再求值.x²y²-4)(-x²y²-4)-4(xy-1/2)·(xy-1\2),其中x=1,y=-2.
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