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The domain of the real valued function f(x) for which $4^{f(x)}+4^{1-f(x)}=4^x$ is |
(-1 , 1] [1, ∞) (-∞, 1] (-∞, -1] |
[1, ∞) |
$4^{f(x)}+\frac{4}{4^{f(x)}}=4^x$ $(4^{f(x)})^2-4^{xf(x)}+4=0⇒u^2-4^xu+4=0\,\,\,∵D≥0$ $4^{2x}≥4^2⇒2x≥2⇒x≥1$ |
