6. A linear function f(x) contains the coordinates (-9, 4) and (6,4). Joy says f(x) is a horizontal
line, and Lu says f(x) is a vertical line. Which student correctly described the function?
Explain.
Joy because (-9.4) and (6,4) would have a slope of zero which is a horizontal line,
O Joy because (-9,4) and (6,4) would have a slope of zero who is a vertical line.
O Lu because (-9,4) and (6.4) would have a slope of zero which is a horizontal line
O Lu because (-9,4) and (6.4) would have a slope of zero which is a vertical line.