## anonymous 4 years ago if the slope of a line is negative. does that mean the change in x is negative or the change in y??

change in y

2. anonymous

why?

3. anonymous

Slope is defined by conventoin as rate of change of y wrt x

4. anonymous

huh?

5. asnaseer

positive slope implies y increases as x increases negative slope implies y decreases as x increases

you can say it like that, but it's possible that x increases and slope is zero

|dw:1328378057184:dw|

8. asnaseer

yes - that is different case: zero slope means y remains the same as x increases

that is one possibility

10. anonymous

what do you mean by y increasing and x decreasing?

12. asnaseer

|dw:1328378129883:dw| if you look at this line, the slope is negative. it could be calculated by either working out the changes from A to B OR by working out the changes from B to A. so, from A to B we get:$slope=\frac{1-5}{5-1}=\frac{-4}{4}=-1$ and from B to A we get:$slope=\frac{5-1}{1-5}=\frac{4}{-4}=-1$

13. asnaseer

so you can see that a negative slope can be worked out with either a negative change in x or a negative change in y. it depends on how you pick your two points.