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If-f-x-1-x-1-and-g-x-x-find-domain-and-range-of-g-f-x-




Question Number 92597 by john santu last updated on 08/May/20
If f(x)=(1/(x−1)) and g(x)=(√x)   find domain and range of   g(f(x)) .
$$\mathrm{If}\:\mathrm{f}\left(\mathrm{x}\right)=\frac{\mathrm{1}}{\mathrm{x}−\mathrm{1}}\:\mathrm{and}\:\mathrm{g}\left(\mathrm{x}\right)=\sqrt{\mathrm{x}}\: \\ $$$$\mathrm{find}\:\mathrm{domain}\:\mathrm{and}\:\mathrm{range}\:\mathrm{of}\: \\ $$$$\mathrm{g}\left(\mathrm{f}\left(\mathrm{x}\right)\right)\:. \\ $$
Commented by jagoll last updated on 08/May/20
g(f(x)) = (1/( (√(x−1))))   D_(g(f(x)))  ∩ R_(f(x))  ≠ ∅  x > 0 ⇒1 < x < ∞   R_(g(f(x)))  > 0 ⇒ 0<y<∞
$$\mathrm{g}\left(\mathrm{f}\left(\mathrm{x}\right)\right)\:=\:\frac{\mathrm{1}}{\:\sqrt{\mathrm{x}−\mathrm{1}}}\: \\ $$$$\mathrm{D}_{\mathrm{g}\left(\mathrm{f}\left(\mathrm{x}\right)\right)} \:\cap\:\mathrm{R}_{\mathrm{f}\left(\mathrm{x}\right)} \:\neq\:\varnothing \\ $$$$\mathrm{x}\:>\:\mathrm{0}\:\Rightarrow\mathrm{1}\:<\:\mathrm{x}\:<\:\infty\: \\ $$$$\mathrm{R}_{\mathrm{g}\left(\mathrm{f}\left(\mathrm{x}\right)\right)} \:>\:\mathrm{0}\:\Rightarrow\:\mathrm{0}<\mathrm{y}<\infty \\ $$

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