Answer:
13/19
Step-by-step explanation:
To find the reciprocal, flip the number.
The reciprocal of 19/13 is 13/19
~
First of all, we can observe that

So the expression becomes

This means that the expression is defined for every 
Now, since the denominator is always positive (when it exists), the fraction can only be positive if the denominator is also positive: we must ask

Since we can't accept 3 as an answer, the actual solution set is
![(-\infty,-2] \cup [2,3) \cup (3,\infty)](https://tex.z-dn.net/?f=%28-%5Cinfty%2C-2%5D%20%5Ccup%20%5B2%2C3%29%20%5Ccup%20%283%2C%5Cinfty%29)
Answer:
The last choice is the correct one
Explanation:
We can solve this question using "difference between squares" which has the following general rule:
a^2 - b^2 = (a+b)(a-b)
For the given question:
p^4 - 16 = (p^2 - 4)(p^2 + 4)
Now, p^2 - 4 can be further factorized using difference between squares, therefore:
p^4 - 16 = (p-2)(p+2)(p^2 + 4)
Hope this helps :)