# Thread: Graphing of rational fn

1. ## Graphing of rational fn

The equation as attach below. i have the problem on question (b). i confuse to determine the value of point of inflection because the i have the ans for
dy/dx = +ve the ans given is dy/dx = -ve. see the circle which i mark.

for your info, when i substitute x=-2 into dy/dx equation, i have the ans as 1/2 which is a +ve as a ans.

so i need a guide how the graph look like.

2. The problem is that you are neglecting the points of discontinuity at x=-1 and x=2. Look below to see what the graph looks like.

So, when selecting a point to "test" whether the derivative is positive or negative, you should be sure to pick a point between x=-1 and x=0.

3. Originally Posted by drumist
The problem is that you are neglecting the points of discontinuity at x=-1 and x=2. Look below to see what the graph looks like.

So, when selecting a point to "test" whether the derivative is positive or negative, you should be sure to pick a point between x=-1 and x=0.