Which situation represents a proportional function? A. Melissa's cell phone plan charges two cents a minute plus a $10 monthly fee. B. Sandra's cell phone plan charges seven cents a minute. C. Holly's cell phone plan charges five cents per minute. She also receives a $5 discount each month. D. Alicia's cell phone plan charges six cents per minute plus a $5 monthly fee.

Step by step explanation

let x be the number of minutes and y be the total charges per month

A. Melissa's cell phone plan charges two cents a minute plus a $10 monthly fee.

y=0.02x+10

B. Sandra's cell phone plan charges seven cents a minute.

y=0.07x

C. Holly's cell phone plan charges five cents per minute. She also receives a $5 discount each month.

y=0.05x-5

D. Alicia's cell phone plan charges six cents per minute plus a $5 monthly fee.

y=0.06x+5

δabc ≅ δdcb by sas because

db ≅ ac . . given (side)

bc ≅ bc . . reflexive property (side)

∠dbc ≅ ∠ acb . . alternate interior angles where transversal bc crosses parallel lines bd and ac (included angle)

guess at question:

a vertical line intersects the graph of g(x,y) = 0 at two points. what conclusion follows about the function f(x) implicitly defined by g(x,f(x)) = 0?

the domain of f(x) cannot include the x coordinate of any such vertical line.

informally, f(x) is not a function, and

g(x,y)=0 cannot be solved for y uniquely.

the relation r = {(x,y) such that g(x,y) = 0} is a function if

for all (a,b) ∊ r and (c,d) ∊ r, a=c implies b=d.

step-by-step explanation: