S.4 Maths. logarithmic question

2007-10-28 11:32 pm
Solve this equation by using logarithmic:
((2^(2X+2)))+((2^(X+2)))=3

Example:
2^X=4
Xlog2=log4
X=(log4)/(log2)
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.
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P.S. Please show steps

回答 (3)

2007-10-28 11:40 pm
✔ 最佳答案
((2^(2X+2)))+((2^(X+2)))=3
2^2x*2^2 + 2^x*2^2 = 3
4*2^2x + 4*2^x = 3
4(2^x)^2 + 4(2^x) - 3 = 0
[2(2^x) -1][2(2^x)+3] = 0
2^x = 1/2 or -3/2 (rejected, since 2^x > 0 for all real x)
2^x = 2^(-1)
x = -1
2007-10-28 11:42 pm
2x+2log2 + x+2log2=3
(2x+2+x+2)log2=3
3x+4log2=log1000
3x+4=log1000/log2
x=((log1000/log2)-4)/3
2007-10-28 11:40 pm
x = -1.

4 (2^(2x)) + 4 (2^(x)) = 3 = 1 + 2


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