Question

What happens to a function multiplied by -1

Answer 1

The sign becomes flipped.

If it's a negative it becomes a positive, if it's a positive then it becomes a negative.

Answer 2

Its graph is reflected over the x-axis.

Explanation:

Multiplying a function by a value gives it a vertical scale factor of that value. When the value is negative, the function's graph is reflected over the x-axis (as well as being scaled).

Multiplying a function by -1 reflects its graph over the x-axis.