Question

What did I do wrong ?

Answer 1

Not ask me for help first :P
j/k j/k

Answer 2

you messed up your domain; [-2,2] is where the function CANNOT exist; domain is (-inf,-2) and (2,inf)

Answer 3

uhhhh is completely correct for part a) you need to solve figure out what can't be inside a log function. Aka a negative number! So you would set up this inequality and solve it to get the domain of the function:
\[x^{2} -4 \ge 0\]

Answer 4

ugh it was so easy and I mssed up so bad, What about the one to one part ?

Answer 5

so I have no idea what you are going for in part b) but to do it you just to need to realize that not matter whether it's positive or negative, the magnitude of x is all that matters. So to prove this you would restrict the domain to only positive number or negative number and show that they are equivalent to each other. Does this make sense?

Answer 6

*realize that it does not

Answer 7

Cause my tutor did somehting similar

Answer 8

Oh I see! it's basically the same thing as I said but instead of restricting the domain at the beginning they did it at the end and showed that it doesn't matter whether it -1 or 1 the result is the same. Thus it can't be 1:1....question you do know what a 1:1 function is correct?

Answer 9

Is its even right ?Or if you do the vertical line test, it should only pass one point ?

Answer 10

and so should I show my teacher and see if he could give me part marks? I mean I did terrible on the test,

Answer 11

So im trying to see where I could get some marks only IF it's right

Answer 12

and its a university prof... I dont want him thinking im just stupid. I shouldve practiced more questions :(

Answer 13

ummm well a 1:1 function needs to pass both the vertical and horizontal line test...if you pass just the vertical you are just a function. As for the partial marks...I'm not so sure that you would get any, unfortunately since not only did he ask you to restrict the domain which is something your tutor didn't really do, but you didn't really execute the method your tutor showed your correctly...so I don't think you'll get anything but you might as well show your teacher right? it couldn't hurt if you got a zero on this?

Answer 14

well your professor shouldn't be thinking that anybody is stupid...people have strengths and weakness and different experiences.

Answer 15

yeah I guess so, I did super poorly on this test. very embarrassing. I hope after I practice harder I'll get a better mark

Answer 16

and horizontal test ?

Answer 17

My tutor was saying it should pass only one ppoint? Vertically ?

Answer 18

So how could a one to one function look like? And thank you for your help:)

Answer 19

no problem! It's great that you are seeking help! ok so you know what a vertical line test is right? It's exactly what you said if you were to draw a vertical line anywhere on the graph it would only intersect the function once. A horizontal line test is the same thing but you draw the line horizontally. Does this make sense?

Answer 20

a 1:1 function must pass both test. But it's better to understand what a 1:1 function actually means! A 1:1 function means that for every x there is a unique y. An example of this is y = x: do you see how for every x there is a unique y?

Answer 21

Okay I see what you mean by 1:1, but how do you mean by special y ?

Answer 22

"special"? You mean when I said that there has to be a unique y? I'll show you an example. So I said y = x is a 1:1 function, so let's use that one. So if x =1, y =1 right? Now since this is a 1:1 function, no matter what x we pick, y will never be equal to 1 as long as we don't pick that particular x (in this case 1).
Compare that to an non 1:1 function such as y = x^2. If x = 2, y = 4 right? But x being 2 is not the only value that will make y =4, x can also be equal to -2 to get y to equal 4.
Does this make sense?

Answer 23

Oh yes it does make sense