1.
圖片參考：http://imgcld.yimg.com/8/n/AC07556053/o/151112240742613872134890.jpg
2.
圖片參考：http://imgcld.yimg.com/8/n/AC07556053/o/151112240742613872134891.jpg
兩題都要有詳解過程
謝謝^^
兩題高一指數
2011-12-25 7:01 am
回答 (2)
2011-12-25 8:49 am
2011-12-25 8:33 am
1
Sol
f(x)=2^(x+1)-4^x
=－2^(2x)+2*2^x
=－[2^(2x)－2*2^x]
=－[2^(2x)－2*2^x+1]+1
=－(2^x－1)^2+1
－1<=x<=2
1/2<=2^x<=4
－1/2<=2^x－1<=3
0<=(2^x－1)^2<=9
－9<=－(2^x－1)^2<=0
－8<=－(2^x－1)^2+1<=1
－8<=f(x)<=1
2
Sol
4^x=100*3^x
(4/3)^x=100
xlog(4/3)=2
x(2log2－log3)=2
x=3/(0.6020－0.4771)=16.01
16與17之間
Sol
f(x)=2^(x+1)-4^x
=－2^(2x)+2*2^x
=－[2^(2x)－2*2^x]
=－[2^(2x)－2*2^x+1]+1
=－(2^x－1)^2+1
－1<=x<=2
1/2<=2^x<=4
－1/2<=2^x－1<=3
0<=(2^x－1)^2<=9
－9<=－(2^x－1)^2<=0
－8<=－(2^x－1)^2+1<=1
－8<=f(x)<=1
2
Sol
4^x=100*3^x
(4/3)^x=100
xlog(4/3)=2
x(2log2－log3)=2
x=3/(0.6020－0.4771)=16.01
16與17之間
收錄日期: 2021-04-30 16:14:32
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20111224000015KK07426