(2x²y-3xy²)-3(x²y-2xy²)+2（x²y-4xy²）_数学解答

(2x²y-3xy²)-3(x²y-2xy²)+2（x²y-4xy²）,其中x=-1,y=2.
先化简,后求值,

人气：145 ℃　时间：2020-01-28 18:07:36

解答

(2x²y-3xy²)-3(x²y-2xy²)+2（x²y-4xy²）=2x²y-3xy²-3x²y+6xy²+2x²y-8xy²=x²y-5xy²=xy(x-5y)将x=-1,y=2.代入得原式=-2×(-1-10)=22