4x^2y-[2xy-3(xy-x)+4x^2y] 先化简,再求值,其中x=1/3,y=3/4_数学解答

4x^2y-[2xy-3(xy-x)+4x^2y] 先化简,再求值,其中x=1/3,y=3/4

人气：134 ℃　时间：2020-01-28 19:39:43

解答

化简得=4x^2y-[2xy-3xy+3x+4x^2y]
=4x^2y-2xy+3xy-3x-4x^2y
=xy-3x
当x=1/3,y=3/4时,xy-3x=1/4-1=-3/4