Domain of Square Root Rational Function

Find the Domain of the Function

Question:

The domain of the function

\[ f(x)=\sqrt{\frac{(x+1)(x-3)}{x-2}} \]

is

(a) \([ -1,2)\cup[3,\infty)\)
(b) \(( -1,2)\cup[3,\infty)\)
(c) \([ -1,2]\cup[3,\infty)\)
(d) none of these

Solution:

For square root function,

\[ \frac{(x+1)(x-3)}{x-2}\ge0 \]

Critical points are

\[ -1,\;2,\;3 \]

Using sign analysis,

\[ \frac{(x+1)(x-3)}{x-2}\ge0 \]

for

\[ [-1,2)\cup[3,\infty) \]

Note that \(x=2\) is excluded because denominator becomes zero.

Therefore,

\[ \boxed{[-1,2)\cup[3,\infty)} \]

\[ \boxed{\text{Correct Answer: (a)}} \]

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