Please help! 1) Suppose a graph passes the horizontal line test: No horizontal line can be drawn that touches the graph in more than one location. Does this mean that the graph represents a function? If not, is there anything special about a graph that passes the horizontal line test?

2) Dotty and Lionel are making a graph comparing a car's age with its gas mileage. Dotty says the graph should show discrete points because the car's age is stated in whole numbers of years. Lionel says they should make a continuous line because age increases gradually, like time. Which student do you agree with and why?

3) Write two linear functions, f(x) and g(x). For example, f(x) = 3x – 7 and g(x) = –2x + 5. Then see whether f(x) – (–g(x)) is equivalent to f(x)+ g(x). Hint: To find –g(x), just change the signs of all the terms in g(x). Discuss whether you think your results would apply to every function.