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f-x-2-f-x-2-4x-




Question Number 139711 by bramlexs22 last updated on 30/Apr/21
 [f(x)]^2 −[f(−x)]^2 =4x
$$\:\left[\mathrm{f}\left(\mathrm{x}\right)\right]^{\mathrm{2}} −\left[\mathrm{f}\left(−\mathrm{x}\right)\right]^{\mathrm{2}} =\mathrm{4x} \\ $$
Commented by mr W last updated on 30/Apr/21
f(x)=(x/a)+a
$${f}\left({x}\right)=\frac{{x}}{{a}}+{a} \\ $$
Commented by hknkrc46 last updated on 30/Apr/21
f(x) = ax + b ⇒ f(−x) = −ax + b  ⇒ f^2 (x)−f^2 (−x) = 4abx = 4x  ⇒ ab = 1  f (x) = ax + (1/a) = (x/b) + b
$$\boldsymbol{{f}}\left(\boldsymbol{{x}}\right)\:=\:\boldsymbol{{ax}}\:+\:\boldsymbol{{b}}\:\Rightarrow\:\boldsymbol{{f}}\left(−\boldsymbol{{x}}\right)\:=\:−\boldsymbol{{ax}}\:+\:\boldsymbol{{b}} \\ $$$$\Rightarrow\:\boldsymbol{{f}}^{\mathrm{2}} \left(\boldsymbol{{x}}\right)−\boldsymbol{{f}}^{\mathrm{2}} \left(−\boldsymbol{{x}}\right)\:=\:\mathrm{4}\boldsymbol{{abx}}\:=\:\mathrm{4}\boldsymbol{{x}} \\ $$$$\Rightarrow\:\boldsymbol{{ab}}\:=\:\mathrm{1} \\ $$$$\boldsymbol{{f}}\:\left(\boldsymbol{{x}}\right)\:=\:\boldsymbol{{ax}}\:+\:\frac{\mathrm{1}}{\boldsymbol{{a}}}\:=\:\frac{\boldsymbol{{x}}}{\boldsymbol{{b}}}\:+\:\boldsymbol{{b}} \\ $$

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