Question

im graphing functions that i need to find the domain and range of, ( I know what domain and range is) but is there a quick way to figure it out and writing it correctly in interval notation?) I think im over thinking it, but i want to make sure im doing my work correctly...

Answer 1

where's your work

Answer 2

ill upload the file hold on.

Answer 3

its basically like graphs like \[y=\sqrt{x} , y=\sqrt[3]{x?} , y= e ^{x} , y=lnx , y=2^5 , y= 1/x , y= x^2-4 , y= x^2+4x+3, y=sinx , y= \sqrt{x-2}, y=\sqrt{4-x^2 , and y=|x+3|-2 }\]

Answer 4

? are you trying to say that x = your domain and y = your range

because you don't write it that way

Answer 5

2aroub, u been drinking...?

Answer 6

its basically like graphs like \[y=\sqrt{x} ,
y=\sqrt[3]{x?} , y= e ^{x} , y=lnx , y=2^5 ,
y= 1/x , y= x^2-4 , y= x^2+4x+3, y=sinx ,
y= \sqrt{x-2}, y=\sqrt{4-x^2 , and y=|x+3|-2 }\]

Answer 7

ahh i dont think you can see them all, but basically its like im not sure if im calculating them right, and if i can do one correctly i can probbaly figure out the rest on my own.

Answer 8

well what did youdo for y = sqroot(x)

Answer 9

i wrote that x is greater than or equal to 0 and wrote [0, the infinity sign)

Answer 10

The short answer is u have to figure it out, there is no quick way...

Answer 11

i know the rules for some of them but its like im kind of stuck on how to figure out the others..

Answer 12

especially the range, i know its pretty simple but its been a while since ive done these problems and im probably just over thinking but i dont want to get them all wrong because of a simple mistake...

Answer 13

graphing wold be the easiest

Answer 14

i graphed them, and im looking at them, but i feel stuck, and its frustrating because i dont know why i cant figure it out, (i never liked graphs)

Answer 15

your domain is going to be what values can x be and range will be all y values

Answer 16

See, after a while u just get to know most of them....

Usually its just R in and out but of course they are putting all these ones to get u to learn the odd ones...

Answer 17

so your domain for like sq root is usually going to be 0,infinity

Answer 18

U need to know what the graphs of things line ln x and e^x look like without having to graph them...

Answer 19

I understand that, but for example \[y=\sqrt[3]{x?} \] would the domain be \[\left( -\infty, \infty \right)\]? but what would the range be , the same?

Answer 20

cube root -8?

Answer 21

lol ok i just sounded stupid, how would you right the range then.

Answer 22

R

Answer 23

write* eep

Answer 24

Estudier might know but i'm not 100 % sure i know you could find it by calculus but as for now i guess all you can assume is that since domain can only be positive that the numbers generate will be positive to infinity

Answer 25

Domain for cube root is R as well.

Answer 26

Positive is just for square root under radical

Answer 27

so you could like evaluate to show how you found the rane by like saying f(0) = ... and then f(infinity)=

Answer 28

so \[\left[ 0,\infty \right]\] for both?

Answer 29

No need to evaluate, just state that domain and range is R.

Answer 30

i feel like i understand what you are trying to say but its frustrating lol

Answer 31

What's this obsession with infinity?

Answer 32

yeah you could just say but my teacher would be like "HOW DID YOU COME TO THE ASSUMPTION, YOU DIDNT SHOW,WRONG"

Answer 33

because your values can go to infinity with those functions

Answer 34

idk why the hes says the domain can be all real numbers for square roots

Answer 35

i feel like in pre cal i used infinity a lot, and my teacher would include it alot in interval notation, now that im doing work for Ap calc, i feel nervous im trying to refreshen my memory, and like outkast said alot of these functions can go to infinity so i just assumed i would need it in these cases.. but im not sure which is why im asking

Answer 36

idk why the hes says the domain can be all real numbers for square roots

We have been talking about cube roots...

Answer 37

U know the domain and the range are sets, right?

Answer 38

that is just one example... i have 12 to do in total lol. im trying to figure out how to do a feel to continue with the rest.

Answer 39

and yes.

Answer 40

The set R is an infinite set.

Answer 41

ie all real numbers....

Answer 42

And u know infinity is not a number, right?

Answer 43

yess.... im not that slow -_- im just trying to refreshen my memory on this im not an idiot...

Answer 44

I'm not entirely talking to u (and I am not saying u r slow).

There seems to be some misunderstandings here, it would be good to clear them up...

Answer 45

yeah it would be good lol. ugh im just frustrated with these graphs

Answer 46

Well, let's go 1 by 1...

y = sqrt x was first, was it?

Answer 47

yes

Answer 48

U got that one or not?

Answer 49

i know it cant be negative numbers.. i wrote 0,positive infinity for both...

Answer 50

Personally I would say x>=0 but if that is what u have been taught to put....

Answer 51

And because of that y is also >=0

Answer 52

Because I don't understand what sqrt(infinity) means...

Answer 53

thats what i wrote i didnt know how to put it in interval

Answer 54

not sqrt infinity, but in these cases the numbers can be endless the line goes on thats what they mean

Answer 55

U can write [0, infinity) as an "interval" if u want to.

To me it makes no sense as a domain because u cannot take the sqrt of infinity.

Answer 56

ur not taking the sqrt of infinity it just means the lines goes on it could be any number going on

Answer 57

I understand what u r saying but the domain is a set, the set is called R.

U are writing an interval, which is fine, but then saying that is the domain which is where u lose me.

Look here

http://en.wikipedia.org/wiki/Domain_of_a_function

Answer 58

Not R in this case, 0 or positive integers, sorry...t

Answer 59

i see what u are saying.

Answer 60

The set of positive integers plus zero I would usually call N

Answer 61

The problem here maybe that I don't really know what it is u have been taught up to now......

Answer 62

Have u encountered these terms like R, Z, N before..?

Answer 63

I remember being taught this, but that was a while back, now im preparing for AP calc and im looking at this in terror lol. i did, but briefly

Answer 64

U said u knew that domain and range is a set, so I just assumed..

Answer 65

What is AP Calc?

Answer 66

Advanced placement calculus AB?

Answer 67

placement to uni?

Answer 68

yeah,

Answer 69

Then I think u should go with the correct way and describe the domain and range as sets....

Answer 70

hmm, i shall keep looking the domain and range is the only thing i left blank :/

Answer 71

Do u know how to use Wolfram?

Answer 72

no

Answer 73

It will make your life easier for the graphs...

Answer 74

Or simpler

http://www.wolframalpha.com/input/?i=y%3De^x

Answer 75

U just type in the function and it will give u the graph and a bunch other stuff...

Answer 76

thank you !

Answer 77

Last thing, u can specify the domain and range of plot like this (try with some numbers of your own).

Answer 78

http://www.wolframalpha.com/input/?i=plot+y%3De^x%2C+x%3D-100...100%2C+y%3D+10000..1000

Answer 79

Careful with the cube root, doesn't quite work in the way u would normally expect

Answer 80

U have to do this way (Re means reals)

http://www.wolframalpha.com/input/?i=Re+y%3D+x^3+

Answer 81

Anyway, hope all goes well for u...

Answer 82

It seems that I have misled u somewhat, u are apparently permitted to describe a function range and domain simply using interval notation with (-inf, inf) being R.

Seems to me u should not get into trouble the other way, however, since that is also correct.