1/2x-[(2x-2/3y²)-(-3/2x+1/3y²)],其中x=1/4,y=-1

题目

1/2x-[(2x-2/3y²)-(-3/2x+1/3y²)],其中x=1/4,y=-1

答案

原式=1/2x-(2x-2/3y²+3/2x-1/3y²)
=1/2x-(7/2x-y²)
=1/2x-7/2x+y²
=-3x+y²
=-3×1/4+(-1)²
=1/4