no slope or m=0, means the line is horizontal, having the same y-value for all x
so it doesnt depends of x
2 and 4 arent correct
The answer you have for the first problem is correct. In the second problem, however, your are asked to find the equation to a line that goes through the point that has no slope. No slope implies that the line is vertical. Thus, the equation is .
Number 3 is correct.
Number 4 is wrong. If I use the formula that I have written at the beginning og this post, I have
This is a horizontal line, as is expected given a slope of 0.