题目

如图，已知二次函数，直线，直线（其中，为常数）；.若直线的图象以及的图象所围成的封闭图形如阴影所示. （Ⅰ）求； （Ⅱ）求阴影面积s关于t的函数的解析式； （Ⅲ）若过点可作曲线的三条切线，求实数m的取值范围. 答案：（1）（2） ，    （3）所求的实数m的取值范围是 解析:（I）由图可知二次函数的图象过点（0，0），（1，0） 则，又因为图象过点（2，6）∴6=2a ∴a=3 ∴函数的解析式为  ………3分 （Ⅱ）由得 ∵，∴直线与的图象的交点横坐标分别为0,1+t ,  ……………5分 由定积分的几何意义知：  ，          Domestic (驯养的) horses now pull ploughs, race in the Kentucky Derby, and carry police. But early horses weren’t tame (驯服的) enough to perform these kinds of tasks. Scientists think the first interactions humans had with horses were far different from those today.Thousands of years ago, people killed the wild horses that lived around them for food. Over time, people began to catch the animals and raise them. This was the first step in domestication.As people began to tame and ride horses, they chose to keep those animals that had more desirable characteristics. For example, people may have chosen to keep horses that had a gentle personality so they could be ridden more easily. People who used horses to pull heavy loads would have chosen to keep stronger animals. Characteristics like strength are partly controlled by the animals’ genes. So as the domesticated horses reproduced, they passed the characteristics on to their young. Each new generation of horses would show more of these chosen characteristics.Modern-day horse breeds（种类） come in a wide variety of shapes and sizes. This variety didn’t exist in the horse population before domestication. The Shetland horse is one of the smallest breeds— typically reaching only one meter tall. With short, strong legs, the animals were bred to pull coal out of mine shafts (矿井) with low ceilings. Huge horses like the Clydesdale came on the scene around 1700. People bred these heavy, tall horses to pull large vehicles used for carrying heavy loads.The domestication of horses has had great effects on societies. For example, horses were important tools in the advancement of modern agriculture. Using them to pull ploughs and carry heavy loads allowed people to farm more efficiently. Before they were able to ride horses, humans had to cross land on foot. Riding horses allowed people to travel far greater distance in much less time. That encouraged populations living in different areas to interact with one another. The new form of rapid transportation helped cultures spread around the world.【小题1】Before domestication horses were ______.A．caught for sports B．hunted for foodC．made to pull ploughsD．used to carry people【小题2】The author uses the Shetland horse as an example to show ______.A．it is smaller than the Clydesdale horseB．horses used to have gentle personalitiesC．some horses have better shapes than othersD．horses were of less variety before domestication【小题3】Horses contributed to the spread of culture by ______.A．carrying heavy loadsB．changing farming methodsC．serving as a means of transportD．advancing agriculture in different areas【小题4】The passage is mainly about _______.A．why humans domesticated horsesB．how humans and horses needed each otherC．why horses came in different shapes and sizesD．how human societies and horses influenced each other