Which of these are functions?

a graph of an oval a graph of a horizontal line a graph of an upside-down standard parabola


Which of these are functions?  Draw rough sketches of the graphs so you can do the vertical line test:

y = -( 2 / 3 )x + 4

y = 5x - x^2


What about these?

a graph of an "m"-like curve   a graph of an oval