Answer: First option and last option.
Explanation:
By definition, an equation of direct proportion has the following form:
Where k is the constant of proportionality.
The equation of the line
, where m is the slope and b the y-intercept.
When b=0, means that the line passes through the origin. Therefore, it would be:
(which is similar to
)
Then, the slope of the line would be the constant of proportionality.
By definition, the slope can be positive or negative.
Keeping on mind the information above, you can see that the equation that have that form are: