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Step 1 :
\Definition :
\The derivative of a function f with respect to x is denoted by
.
if this limit exists.
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Step 2 :
(a) The function is
.
Find
:

The derivative of a function.
\
Multiply numerator and denominator by
. \ \

\ \




Substitute the limit.
\
\ \

Step 3 : \ \
\(b) The inverse function is 
The domain of a function is all values of
, those makes the function mathematically correct.
The denominator of the function should not be zero and square root should not be negative number. \ \
\
. \ \
.
The domain of the inverse function is
. \ \
\
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Solution :

The domain of the inverse function is
.