Question

Find the domain of the logarithmic function f(x) = log4 (x – 3).

Answer 1

A.Any real numbers

B.
Positive real numbers
C.Negative real numbers

D.x > 3

Answer 2

@ganeshie8

Answer 3

Can you take the log of any number?

Answer 4

is it c?

Answer 5

No.

Can you take the log of any number?

Answer 6

yes

Answer 7

wait no no u cant

Answer 8

That's incorrect.

For example, you cannot take the log of -1; because 10 to no power will give you -1. (I was using base 10..but makes no difference what base you are using).

Answer 9

ohh

Answer 10

So the underlining question is...what kind of numbers can you take the log of?

Answer 11

all reall numbers

Answer 12

In your probelm, x cannot be -7, because x-3 will be -7-3 = -10, and you can't take the log of -10.

Answer 13

You cannot take the log of all real numbers.

We just discussed that you cannot take the log of -1.

Back to our initial question...think as to what numbers can you take the log of?

Answer 14

positive real numbers?

Answer 15

exactly! You can't even take the log of 0....because 10 to no power gives you 0.

So since you can only take the log of a positive real number, then in your function, we better make sure that x - 3 > 0.

Answer 16

So what will be domain of y = log (x-3)?

Answer 17

what are all the numbers x in the domain for y = log(x - 3)?

Answer 18

numbers 1+ or all positive real numbers

Answer 19

that is true for y = log x

we are looking at the function y = log (x - 3). Since we can only take the log of a positive number, then we must make sure that x - 3 > 0!! Agree?

Answer 20

yeah my bad i didnt see the question right i cant put 1 or 2

Answer 21

so whats the right answer to this question?

Answer 22

D

Answer 23

x>3

Answer 24

correct.

Answer 25

wow your really smart

Answer 26

Thanks for help

Answer 27

It has nothing to do with smart. It has to do with understanding the log function...that we can only take the log of a number greater than 0 (regardless of the base).

Answer 28

And to understand why that is true; not memorize.

Answer 29

Look at the graph of y = log (x-3).

Answer 30

what about a number greater then or equal to 0 ?

Answer 31

you can see from the graph, that x exists for x>3, only.

Answer 32

yes

Answer 33

OK. Good luck!

Answer 34

i got a other one i did y=1/x-2 and i put all real numbers exept 2 for a awnser

Answer 35

Is the entire x-2 in the denominator? y = 1/(x-2)?

Answer 36

?

Answer 37

yes

Answer 38

Then you are correct, if asked for the domain. x van be any real number other than 2, as the function is undefined at x = 2.

Answer 39

So you are correct for that problem.

Answer 40

thanks:D

Answer 41

welcome.