已知二次函数y=x2-3x-1的图象经过点M（m，-2），试求代数式m3-m2-4m+2+
|
∵二次函数y=x2-3x-1的图象经过点M（m，-2），则m2-3m+1=0；
∴m2+1=3m，
∴m3-m2-4m+2+3 m2+1
=m（m2+1）-（m2+1）-5m+3+1 m
=3（m2-3m+1）+m+1 m
=m2+1 m
=3m m
=3，即m3-m2-4m+2+
=3．3 m2+1
| 完形填空。 | ||||
| What kind of home will we live in the future? 1 can be sure,but scientists are working 2 new ideas now. Some scientists are 3 about building whole cities under huge glass domes (圆顶). 4 , advanced heating and cooling systems will be 5 to control the weather in the domes. 6 , there will never be any 7 or snow,and the temperature will always be 8 . Perhaps everyone willlive in vertical(垂直的) cities-high rises 9 are so large that they can 10 all the necessities oflife. Since vertical cities will use 11 land than flat cities,and provide homes 12 more people,it will be practical for small countries that have 13 population. 14 idea that will be helpful to small countries is the 15 city. Monaco has already built homes,stores,and offices 16 the water of the Mediterranean Sea. There are some people who think that we will go back to 17 in caves. 18 the caves of the future will be very different from the caves of the Stone Age. Farms and parks will be on the land 19 the cave city. When people want to go to the country or to a park,a short ride in a 20 will take them there. | ||||
|