Can someone help me with this question.

C

Step-by-step explanation:

A function means that a graph cannot have repeating x values, so to test if something is a function we do the horizontal line test. You simply draw a vertical line and if the graph touches it twice it is not a function.

1/2*qr*rs

step-by-step explanation:

for this case we must apply distributive property to the following expression:

the distributive property states that:

then, when applying the property we have to multiply the -2 for each term within the parenthesis: