#### Answer

a. These two numbers are opposite reciprocals.
b. These two numbers are not opposite reciprocals.
c. These two numbers are not opposite reciprocals.

#### Work Step by Step

a. We can check if two numbers are opposite reciprocals by multiplying them together to see if their product equals $-1$.
$-2(\frac{1}{2})$
Multiply to simplify:
$-\frac{2}{2}$
Simplify the fraction:
$-1$
The product of the two numbers is $-1$; therefore, these two numbers are opposite reciprocals.
b. We can check if two numbers are opposite reciprocals of one another by multiplying them together to see if their product equals $-1$.
$(\frac{1}{4})(4)$
Multiply to simplify:
$\frac{4}{4}$
Simplify the fraction:
$1$
The product of the two numbers is not $-1$; therefore, these two numbers are not opposite reciprocals.
c. We can check if two numbers are opposite reciprocals of one another by multiplying them together to see if their product equals $-1$.
$5(-5)$
Multiply to simplify:
$-25$
The product of the two numbers is not $-1$; therefore, these two numbers are not opposite reciprocals.