We'll recall the identity: log a (b) = 1/log b
(a)
Therefore, using this property, we'll create matching
bases in the given equation:
1/ log 2 (x) + 1/log 2 (2x) =
1/log 2 (4x)
We'll recall the product property of the
logarithms, such as:
log 2 (2x) = log 2 (2) + log 2
(x)
log 2 (2x) = 1 + log 2
(x)
log 2 (4x) = log 2 (4) + log 2
(x)
log 2 (4x) = 2 + log 2
(x)
We'll substitute log 2 (x) by
t:
1/t + 1/(1 + t) =
1/(2+t)
The equation will
become:
(1+t)(2+t) + t(2+t) - t(1+t) =
0
We'll remove the brackets:
2
+ 3t + t^2 + 2t + t^2 -t - t^2 = 0
We'll eliminate like
terms:
t^2 + 3t + 2 + 2t - t =
0
We'll combine like
terms:
t^2 + 4t + 2 = 0
We'll
apply quadratic formula:
t1 = [-4 + sqrt(16 -
8)]/2
t1 = (-4 + 2sqrt2)/2
t1
= sqrt2 - 2
t2 = -sqrt2 -
2
log 2 (x) = sqrt2 - 2 => x = 2^(sqrt2 -
2)
log 2 (x) = -(sqrt2 + 2) => x = 1/2^(sqrt2 +
2)
Since the x values are positive and they
are different from 1, we'll accept them as solutions of the given equation: {2^(sqrt2 -
2) ; 1/2^(sqrt2 + 2)}.
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