Eleanor notices the cost of a gallon of gas is $3.85. She searches the Internet for the cost of a gallon of gas 50 years ago and finds that is was $0.89. What is the difference in costs, and why?

A The difference is $2.96 because 3.85 + 0.89 = 2.96.
B The difference is $2.96 because 3.85 − 0.89 = 2.96.
C The difference is $4.74 because 3.85 + 0.89 = 4.74.
D The difference is $4.74 because 3.85 − 0.89 = 4.74.

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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: