Question

When you multiply a function by -1, what is the effect on its graph?

Answer 1

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Answer:

  B.  The graph flips over the x-axis

Step-by-step explanation:

When you plot the coordinate pair (x, y), you plot the point 'y' units above the x-axis. If you change the sign of that (multiply the function by -1), then the point becomes (x, -y), and is plotted 'y' units below the x-axis.

The graph flips over the x-axis.

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Attached is an example of a function with its original graph (red) and the graph after being multiplied by -1 (blue). The blue graph is a reflection of the red graph across the x-axis.