1.

Find the domain of each of the following real fuctions: (i) `f(x)=sqrt(x-3)` (ii) `g(x)=sqrt(4-x^(2))` (iii) `h(x)=(1)/(sqrt(1-x))`.

Answer» (i) We have, `f(x)=sqrt(x-3)`.
Clearly, f(x) is defined for all real values of x for which `x-3ge0,i.e.,xge3`.
`:."dom "(f)=[3,oo)`.
(ii) We have, `g(x) =sqrt(4-x^(2))`
Clearly, g(x) is defined for all real values of x for which `(4-x^(2))ge0`
But, `(4-x^(2))ge0implies-(4-x^(2))le0`
`impliesx^(2)-4le0implies(x+2)(x-2)le0`
`implies-2lexle2impliesx""in[-2,2]`.
`:."dom "(g)=[-2,2]`.
(iii) We have, `h(x)=(1)/(sqrt(1-x))`
Clearly, h(x) is defined for all real values of x for which `(1-x)gt0`.
But, `1-xgt0implies1gtximplieslt1impliesx""in(-oo,1)`.
`:."dom "(h)=(-oo,1)`.


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