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Which of the following is true for the validity of the limit of the function \lim _{x \rightarrow-8} \frac{x^2+6 x-16}{x+8} ?

Option: 1

For every point in the domain of the function and  x=-8


Option: 2

For every point in the domain of the function except  x=-8


Option: 3

For every point in the domain of the function only 

 


Option: 4

None of the above


Answers (1)

Note the following points.

  • The domain of any function is the set of all its inputs for which the function itself remains valid.

  • The limit of any function \lim _{x \rightarrow p^{+}} f(x) may exist even when f(x) is not defined at  x=p

Now, the provided function f(x)=\frac{x^2+6 x-16}{x+8} can be reduced as follows.

f(x)

=\frac{x^2+6 x-16}{x+8}

=\frac{x^2+8 x-2x-16}{x+8}

=\frac{x(x+8)-2 (x-8)-16}{x+8}

=\frac{(x+8) (x-2)}{x+8}

=(x-2) ,  x \neq -8

Evidently, the function f(x) becomes invalid at  x=-8. So, the domain of the function f(x) does not have the point x=-8

But the limit of the function exists as evident from the following calculation.

\lim _{x \rightarrow-8} \frac{x^2+6 x-16}{x+8}

=\lim _{x \rightarrow-8} \frac{(x+8)(x-2)}{x+8}

=\lim _{x \rightarrow-8} (x-2)                      [ x\neq-8]

=-8-2

=-10

Thus, the limit of the function  \lim _{x \rightarrow-8} \frac{x^2+6 x-16}{x+8}    exist for every point in the domain of the function and x=-8

 

 

 

 

 

Posted by

Kshitij

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