Question

Find the domain of the function and express the answer in interval notation: f(x)=3x-9

Answer 1

(infinity,-infinity) as the answer

Answer 2

really?

Answer 3

\[(-\infty,\infty)\]

Answer 4

i really dont know how to do this, i just learn how to figure it out when there is a square root, and i can figure it when it is dividing. I havent had a math class since 2005. so its taken me some time to figure this out. im sorry

Answer 5

in interval notation the smaller number goes to the left

Answer 6

didnt you just write the same answer as me? i just used words

Answer 7

no

Answer 8

\[(-\infty,\infty)\]

Answer 9

why does the smaller number go to the left? is it because the negative is on the left with the graph for x-values?

Answer 10

we list the smaller number first because it comes before the bigger number

Answer 11

you know its like writing a set
when we write the natural numbers we start with the smaller one
N={1,2,3,...}
because we want to show a pattern
(-inf,inf) is just a set of numbers as well

Answer 12

sad part is, i know the smaller number is first then the bigger number, thats logic and i should of remember that. i just dont understand how to find the domain and write the answer in interval notation.

Answer 13

anything in this form
\[f(x)=a_nx^n+a_{n-1}x^{n-1}+a_{n-2}x^{n-2}+ \cdot \cdot \cdot +a_1x+a_0\]
is called a polynomial
and a polynomial is defined for all real numbers and therefore the domain is all real numbers
using interval notation we say: \[(-\infty,\infty)\]

Answer 14

all those a's are just constants by the way

Answer 15

all those should be positive integer exponents

Answer 16

or neutral integer exponents lol

Answer 17

i know the form, my teacher showed it to because i told him i didnt understand this. i can figure this out when dividing and when there is a squareroot.

Answer 18

n just needs to be a non-negative integer

Answer 19

right

Answer 20

positive or neutral

Answer 21

yes

Answer 22

tell your teacher that all these problems are bull hockey

Answer 23

a function is supposed to come with the domain as part of the definition.

Answer 24

questions that say "find the domain of f" are so much non-sense. if it said "find the largest possible set on which f can act" then it might make some sense

Answer 25

just thought i would mention it

Answer 26

yeah i dont think im going to say that to my college teacher...

Answer 27

if they are any good they would agree with you ;)

Answer 28

i understand everything else that he throws at me, but this i dont get

Answer 29

thanks for the help, i think the these 4 questions i asked about these with help me finish my homework.

Answer 30

no i was kidding when i said "tell your teacher..."
when you see a function and are asked for the domain, start by thinking "all real numbers"

Answer 31

like "innocent until proven guilty"

Answer 32

lol

Answer 33

then you usually only have to worry about two things, at least until you get further
1) no zeros in the denominator
2) no negative numbers inside a radical

Answer 34

ok thanks, i kinda figured that you were kidding, plus i only have to put with this class for 7 more day...lol

Answer 35

7 more days then freedom!

Answer 36

only fret about those things. if you see no radicals, no denominators, say "all real numbers" and have a nice day. that is it

Answer 37

if you see a denominator, make sure it is NOT zero
if you see a radical, make sure what is inside is greater than or equal to zero. finis

Answer 38

you have a nice day too