Question

化简求值:3x的平方y的平方+2xy-7x的平方y的平方-3/2xy+4x的平方y的平方-2，其中x=2，y= 1/4 现在要 急！~

Answer 1

3x²y²+2xy-7x²y²-3/2xy+4x²y²-2
=1/2xy-2
x=2,y=1/4带入，得
=1/4-2
=-7/4

Answer 2

先化简：3x²y²+2xy-7x²y²-2/3xy+2+4x²y²
=3x²y²+4x²y²-7x²y²+2xy-1又1/2xy+2
=1/2xy+2
解得：1/2×2×1/4
=1/4+2
=9/4