PDA

View Full Version : What did I do wrong?

UrbanXrisis
Sep29-04, 08:30 PM
Why did I get this Math Question Wrong?

http://home.earthlink.net/~urban-xrisis/IMG_0373.jpg
matt grime
Sep30-04, 03:32 AM
Is it supposed to be [0.5x], meaning ceiling? It's hard to make out on my screen
Leong
Sep30-04, 03:34 AM
i get the same graph as you did. maybe you should ask the fella who marked you question.
SGT
Sep30-04, 05:52 AM
I think the required answer is a straight line segment from the point (-1,-2) to the point (1,2)
matt grime
Sep30-04, 06:02 AM
if you look at the scanned image, SGT, the format implies that it ought to be ceiling(0.5x) that is plotted, not 0.5x, i think, though it is a little vague,
UrbanXrisis
Sep30-04, 06:25 AM
that symbol is the greatest integer function.
SGT
Sep30-04, 06:39 AM
OK, I had not understood the meaning of the brackets. I think the solution is in the attached picture.
matt grime
Sep30-04, 07:09 AM
That is also not correct since 0.5*2=1, and ceiling(1) is 1, not two as your diagram shows.
SGT
Sep30-04, 08:38 AM
That is also not correct since 0.5*2=1, and ceiling(1) is 1, not two as your diagram shows.

My mistake. I was plotting y =[x], instead of y = [0.5x]. If the brackets really mean ceiling, your solution seems correct.
HallsofIvy
Sep30-04, 02:01 PM
Why did I get this Math Question Wrong?

http://home.earthlink.net/~urban-xrisis/IMG_0373.jpg

I notice you have "open circles" at the left endpoint of each interval. Did you mean by that (or did whoever marked you wrong interpret that as) that point was not included in the interval? Since "ceiling" of x is the smallest integer greater than or equal to x, the left endpoint of each interval is included in the interval, but the right endpoint is not.