Chocoholic's Questions

[excal]

You won't need to learn to read tables for Methods, by the way. Nonetheless, it's not difficult at all...

[Chocoholic]

are you talking about that probability table. If so, we have it in our text book but our teacher told us to just ignore it because it's not in the course anymore.

[excal]

are you talking about that probability table. If so, we have it in our text book but our teacher told us to just ignore it because it's not in the course anymore.

And yeah, they have taken it out of the course since 2006.

[Chocoholic]

Find the rule of the image when the graph of the function y=lxl undergoes the following sequences of transformations.
A reflection in the x axis, followed by a translation 3 units in the positive direction of the x-axis and 4 units in the negative direction of the of the y-axis, followed by a dilation of factor 2 from the x-axis.

When I did it I ignored the order of their instructions and did my dilations, reflections then translations and got y=-2lx-3l-4. However, the answer is y=-2lx-3l-8. Why would the answer be different if you do it in the order of their instructions, shouldn't it be the same fuction!?!

[Mao]

reflection in the x axis: y=-|x|

translation 3 units to the right: y=-|x-3|

translation 4 unit down: y=-|x-3|-4

dilation by 2 from x axis (this is the tricky part, you are basically doubling the y coordinate to 2y --> -2|x-3|-8) y=-2|x-3|-8

because you dilated AFTER you translate it, the translation gets dilated in the process, hence the order does matter.

[Chocoholic]

Thanks for clearing this up.

[Chocoholic]

ok, so I've just finished the methods course at school  and before I start checkpoints I wanted to do all the chapter reviews to pinpoint all my weaknesses. That way I won't be trying to fix them while doing checkpoints. Heaps of people in my class have already started checkpoints but thats not how i roll!! I want to improve the yield of doing checkpoints(yes! chemistry has inspired me ) and so I dont think I'm wasting any time doing reviews. I've got an aim to start checkpoints on wednesday. thursday friday.

Anyhow, the point of this is I need help increasing my speed and accuracy. To tell you the truth with M.C questions I used to work it out(which took ages) even if I didn't need to!! That was until about 2 minutes ago( or half an hour once i finish latexing this question).

I worked this question via. process of elimanation. Please tell me if there's any alternative (shorter or easier) way of doing this.

For which one of the following functions does an inverse function not exist?
A)
B)
C)
D)
E)

A- wrong, 1:1 function, therefore inverse exists
B-right answer, not 1:1 function, therefore inverse does not exist
C-wrong, 1:1 function, therefore inverse exists
D-wrong, not 1:1 function, however restriction in domain makes it a 1:1 function
E-wrong, 1:1 function, therefore inverse exists

[shinny]

As for most 'which of the following', it'll obviously have to be by the process of elimination. But it can be quite a fast process if you're able to visualise the graphs given, and the effects of the domains provided. e.g. the linear is obviously not the answer, the parabola would require a domain restriction at 0 to positive or negative infinity, similar for the hyperbola etc.

[Chocoholic]

As for most 'which of the following', it'll obviously have to be by the process of elimination. But it can be quite a fast process if you're able to visualise the graphs given, and the effects of the domains provided. e.g. the linear is obviously not the answer, the parabola would require a domain restriction at 0 to positive or negative infinity, similar for the hyperbola etc.

Thanks shinjitsuzx!!! I visualised them when I worked it out, but I think my explanations above made it sound complicated.  Nonetheless your advice will definately come in handy, thanks for helping me improve!!!

[Mao]

a key to multiple choice questions: they are exam 2, i.e. use your calculator!!! [unless your brain works faster]

[shinny]

Reason why i said visualising is that its probly faster than graphing with a calculator =P (for most of us I hope, given that some of those are pretty easy to visualise)

[Chocoholic]

Thanks Mao. I think for this question my brain would work faster(it took me about 30 seconds to work this one out, personal best!! . I don't even know how to do inverse on my calculator , I only know how to work it out by hand.

[Chocoholic]

Reason why i said visualising is that its probly faster than graphing with a calculator =P (for most of us I hope, given that some of those are pretty easy to visualise)

makes sense! 
I personally like the non-calc exam better. Most of the mistakes I make are because of my calculator!!!

[Mao]

you have said the key to inverses yourself: it has to be 1:1

and you are quite right, this particular question is easier to do by hand

but for MCQ in general, calculator can become very useful

[Chocoholic]

Thanks Mao
i'm officially addicted to methods.....it's my drug. :smitten: