Question 184558
Intercepts are points that are on the axis. So one or the other coordinate of the point must be 0.

So
(0,y)  and (x,0). Solve for them as follows.
Assume x =0, using y=-5x 
y = -5*0 = 0
So the x intercept is (0,0)

Assume y=0. Using y = -5x
0 = -5x
0 = x
So the y intercept is (0,0)

What you have are 'two points that are the same point'. So you cannot plot the line using just the intercepts, since this line passes thru the origin.