# Oxford PAT 2014, Question 8

## 7 thoughts on “Oxford PAT 2014, Question 8”

1. ian says:

hi, may i know how you know e^-x + 2x would have the shape like that in the first graph? i was not taught how to do it in my school and we usually use GC thanks!

2. Jacob says:

No, I mean as in a hole at the point (0,1). Not a line. Because it is x is less than 0 for e to the x, therefore at that point it doesnt exist, so you would draw it as a hole. Maybe the term you use is different, but holes are usually drawn in cases with piecewise functions or 0/0..

1. Ah I see what you mean. You mean like in this video: https://www.youtube.com/watch?v=kJbnEljGZ7c. I don’t think this would be required but it certainly wouldn’t hurt to do that; if you know that the value is not defined at some point then it’s worth marking that on the sketch as long as it doesn’t look confusing. Maybe it’s worth labeling the sketch with a simple phrase like ‘undefined for this value of x’.

3. Jacob says:

Hello again! Out of curiosity, would it be incorrect to have the point: (0,1) on the third derivative drawn as a hole? (Since it is x=0)?

1. Jacob says:

Sorry, I mean since it is x=0 for the (0,-1) curve?

1. By “drawn as a hole”, do you mean, in the sketch of the third derivative, should the two curves be joined by a line between (0,1) and (0,-1)? The answer is: no, there is a gap between them. Is this what you meant?