简答题:收音机每台售价90元，成本为60元，厂方为鼓励销售商大量采购，决定凡是订购量超过100台以上的，每多订购1台，售价就降低1分，但最低价为每台75元。
（1）将每台的实际售价P表示为订购量x的函数；
（2）将厂方所获得的利润p表示为订购量x的函数；
（3）某一商行订购了1 000台，厂方可获利润多少?

A x²+2 B <img width="75" height="51" src="https://www.beizhujiaoyu.com/uploads/202208/20220309101223_1814.jpg" /> C x² D x²-2

A 8 B 7 C 9 D 6

A 1 B -1 C 0 D 2

A -e^-sin(xy) B -sin(xy)e^-sin(xy) C -xcos(xy)e^-sin(xy) D -e^-cos(xy)

A <img width="142" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20220309101239_9456.jpg" /> B <img width="113" height="52" src="https://www.beizhujiaoyu.com/uploads/202208/20220309101241_1644.jpg" /> C <img width="112" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20220309101242_1488.jpg" /> D <img width="142" height="51" src="https://www.beizhujiaoyu.com/uploads/202208/20220309101243_3675.jpg" />

A 不一定可微 B 可微 C 极限不一定存在 D 不一定连续

A x=-1 B x=1 C y=0 D y=1

A 0 B π C <img width="25" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20220309101259_1798.jpg" /> D <img width="74" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20220309101300_0727.jpg" />

A 0 B 1 C 2 D 不存在

A 6π B 3π C 30π D 4 π