HELP ME,我有數學唔識做！

1. 2^2X=0.25
2xlog2=log0.25
= -2log2
2x = -2
x = -1
2. 2^(5x-1)=4^(x+2)
(5x-1)log2 = 2(x+2)log 2
5x-1 = 2x+4
x= 5/3
3. 3^(x+2) = 3^(x+1) + 18
3^(x+2)-3^(x+1)=18
[3^(x+1)] (3-1) =18
3^(x+1)=9
x+1 = 2
x=1

1,) 1:2^2x=0.25
1/4^x=1/4
x=1
2,) 2:2^(5x-1)=4^(x+2)
2/[(2^5x)/2)=2^2(x+2)
2*2/(2^5x)=2^2(x+2)
2^2=2^(2x+4)*2^5x
2^2= 2^(7x+4)
2=7x+4
x=-(2/7)
第3題等我食完飯先..sor

2007-07-16 20:24:39 補充：
想問你個:系分開題目和題號?定還是比既意思?...睇大家既答題..應該系分開題目和題號..禁我再做過,希望吾好禁而吾比我最佳解答v v.....1)2^2x=0.25 4^x=1/4 4^(x+1)=1 4^(x+1)=4^0 x+1=0 x=-1----------------------------------2)2^(5x-1)=4^(x+2) 2^(5x-1)=2^(2x+4) 5x-1=2x+4 x=5/3

2007-07-16 20:25:48 補充：
3)３＾(ｘ＋２）＝３＾(ｘ＋１）＋１８ 3^x*3^2=3^x*3+18 3^x*3(3-1)=18 3^x*3 =9 3^x=3 x=1

1.
2^2x=0.25
2^2x=1/4
2^2x=2^(-2)
2x=-2
x=-1
2.
2^(5x-1)=4^(x+2)
2^(5x-1)=2^(2x+4)
5x-1=2x+4
3x=5
x=5/3
3.
3^(x+2)=3^(x+1)+18
3x3^(x+1)=3^(x+1)+18
3x3^(x+1)-3^(x+1)=18
2X3^(x+1)=18
3^(x+1)=9
3^(x+1)=3^2
x+1=2
x=1