Question

数学必修4 的题 ，不会做。要详解~

Answer 1

4、【答案】C
【解析】
原式=[log（√2） (sin5π/12)]+[log(√2) (cos5π/12)]
=log(√2) [(sin5π/12)cos(5π/12)]
=log(√2) [(1/2)sin(5π/6)]
=log(√2) (1/4)
=-2/(1/2)
=-4

5、【答案】B
【解析】
f(x)=asin(πx+α)+bcos(πx+β)+4
f(1988)=asin(1988π+α)+bcos(1988π+β)+4=3
∴ asin(1988π+α)+bcos(1988π+β)
=asinα+bcosβ
=-1
∴
f(2008)=asin(2008π+α)+bcos(2008π+β)+4
∴ asin(2008π+α)+bcos(2008π+β)+4
=asinα+bcosβ+4
=-1+4
=3

Answer 2

4.原式＝log√2[sin(5π/12)cos(5π/12)]，注：√2是底数。
=log√2[(1/2)sin(5π/6)]
=log√2[(1/2)sin(π/6)]
=log√2(1/4)
=-4，选C
5.易得，f(x)的周期为T=2π/π=2，
从而 f(2008)=f(1988+20)=f(1988)=3，选 B

Answer 3

嗯。。。。。。。。
这是什么时候的题
我完全看不懂。。。

Answer 4