问题
解答题
证明对数换底公式：logbN=
|
答案
证明：令logbN=x，则bx=N，两边同取以a为底的对数得：
=logaN，log bxa
∴x?logab=logaN，
∴x=
，log Na log ba
∴logbN=
成立．log Na log ba
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证明对数换底公式：logbN=
|
证明：令logbN=x，则bx=N，两边同取以a为底的对数得：
=logaN，log bxa
∴x?logab=logaN，
∴x=
，log Na log ba
∴logbN=
成立．log Na log ba
| 完形填空 | |||
| Every school has its own rules. How many 1 are there in your school? At some schools, the students 2 to wear uniforms on school days. But many students don’t like to wear uniforms. They think the uniforms are the ugliest 3 in the world. But the school don’t allow students to wear 4 own clothes at school. So some students draw cartoons or some famous singers on their 5 . They think it is very 6 that everyone wears the same. It is very unfair(不公平的) that teachers and students are wearing 7 . But most of the students 8 the rules. What do you think 9 it? Do you 10 your school uniforms? | |||
| ( )1. A. students ( )2. A. has ( )3. A. clothes ( )4. A. their ( )5. A. school bags ( )6. A. bored ( )7. A. same ( )8. A. obey ( )9. A. of ( )10. A. like | B. rules B. must B. shirts B. they B. books B. boring B. differently B. agree B. about B. make | C. uniforms C. should C. skirts C. them C. uniforms C. interesting C. different C. listen C. by C. wash | D. rulers D. have D. cloth D. themselves D. desks D. interested D. the same D. listen to D. for D. put on |