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2^(-2x) - 3*2^(-x) - 4 = 0 [2^(-x) - 4)]*[(2^(-x)+1]=0 Legge di annullamento del prodotto 2^(-x)=2^2 x= - 2

Equazione esponente

* (1/4)^x - 4 = 3*2^(- x) ≡
≡ (1/2^2)^x - 2^2 - 3/2^x = 0 ≡
≡ (1/2^x)^2 - 3/2^x - 2^2 = 0 ≡
≡ u^2 - 3*u - 2^2 = 0 ≡
≡ (u = - 1) oppure (u = 4) ≡
≡ (1/2^x = - 1) oppure (1/2^x = 2^2) ≡
≡ (2^x = - 2^0) oppure (2^x = 1/2^2) ≡
≡ (log(2, 2^x) = log(2, - 2^0)) oppure (log(2, 2^x) = log(2, 1/2^2)) ≡
≡ (x = i*π/ln(2)) oppure (x = - 2)
VERIFICA al link
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CONTROPROVA al link
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