Question

高一数学，这几题怎么做。求解答。谢谢

Answer 1

1. x∈(0,+∞)

2. f(x)=√x

3. f{f(x)]f(-2)=1/9

三 1：原式=sina(-cosa)(-tana)tana/(-tana)(-sina)=(-cosa)(-tana)=sina

     2: 

     3,   原式=(0.4)^(-1)-(-1/8)^0+2^3+log3 (36/12)

                 =5/2-1+8+1

                 =10.25

Answer 2

12、x>=0
e^x-1>=0
e^x>=1=e^0
x>=0
13、f(x)=√x
设f(x)=x^a
过(2,√2)
2^a=√2=2^(1/2)
a=1/2
f(x)=x^(1/2)=√x
14、1/9
f(1/4)=log2 1/4=log2 2^(-2)=-2
f[f(1/4)]=f(-2)=3^(-2)=1/9
15、
(1) =[sinα(-cosα)(-tanα)(-tanα)]/[tanα(-sinα)]
=sinα
(2) CrA={x|x<3或者x>=7}
CrA∩B={x|2<x<3或者7=<x<8}
(3) =(8×0.008)^(-1/3)-1+(2^4)^(3/4)+[(0.5)^2]^1/2+log3 36 -log3 12
=(2^3)^(-1/3)[(0.2)^3]^(-1/3)-1+2^3+0.5+log3 (3×12)-log3 12
=2^(-1)*(0.2)^(-1)-1+8+0.5+log3 3+log3 12-log3 12
=(0.4)^(-1)+7.5+1
=(2/5)^(-1)+8.5
=5/2+8.5
=2.5+8.5
=11

Answer 3

12、x≥0;
13、y=x^(1/2)
14、f(f(1/4))=f(-2)=3^(-2)=1/9
都是基础题目要自己锻炼作哦