Answer: It is equivalent to a reflection over the y-axis.
Explanation:
We start with the function:
f(x) = m*x + b
where the slope is m.
If we only multiply the slope by -1, the function becomes:
f(x) = -m*x + b
There is a transformation called a reflection over the y-axis.
This works as follows, if we have a function f(x), a reflection over the y-axis is written as:
g(x) = f(-x)
If we apply this to our function, we get:
g(x) = f(-x) = m*(-x) + b
g(x) = -m*x + b
Then we can conclude that:
"When the slope m is multiplied by -1 in f(x)=mx+b, it is equivalent to a reflection over the y-axis"