∵y=-x²/50+162x-21000=-1/50[x²-50*162x]-21000=-1/50[x²-8100x+4050²]+4050²/50-21000=-1/50(x-4050)²+328050-21000=-1/50(x-4050)²+307050函数开口向下,x∈(0,4050)时,单调递...