工艺商场按标价200元销售某种进价为155元的工艺品，每天可售出该工艺品100件．若每件工艺品降价1元，则每天可多售出该工艺品4件．问每件工艺品降价多少元出售，每天获得的利润最大，获得的最大利润是多少元？
设降价x元，可获得利润y元
y=（200-155-x）（100+4x）
所以y=-4x2+80x+4500
∵-4＜0，
∴y有最大值．
当x=-
=10元时，利润最大，y最大=4900元80 2×(-4)
答：每件工艺品下降10元售出，可获得最大利润4900元．
| 完形填空。 | ||||
| When a friend was visiting David, it began 1 . So David told him 2 that night. "You may stay here 3 the night," he said. "OK," answered his friend. But 4 minutes 5 , the friend went out. He didn't tell David where 6 going nor (也没有) did he ask for an umbrella. When David was about 7 , his friend 8 . He was all wet through. "Where 9 you 9 ?" asked David. "I have been 10 ," answered the friend, "to tell my mother that I'll not go home tonight because of the rain." | ||||
|