Question

http://answers.yahoo.com/question/index?qid=20130420191834AA0bAYF Can someone please help me with domain and range for log functions?

Answer 1

can log(0) exist?

Answer 2

I think so.

Answer 3

use a calculator, try it out

Answer 4

no, its undefined look at this graph

http://www.wolframalpha.com/input/?i=log%28x%29

Answer 5

I don't know how to, I just learned this yesterday :x

Answer 6

ok, well as tomo so kindly stated, log(0) does not exist

Answer 7

Ohhh, so it's log10 right?

Answer 8

now try log(1)

Answer 9

0?

Answer 10

now, try log(10), log(100), log(1000)

Answer 11

1,2, and 3?

Answer 12

remember log(x^y) = y*log(x)

remember

10 = 10^1

100 = 10^2

...

Answer 13

anyways, domain refers to all possible x values

we know that 1 exists in the domain, but 0 does not

if x goes to an ridiculously high number, then some value will still exists

if x goes down to a ridiculously low number, like .0000000000000000000001, then it will also still exists,
except until it reaches 0

Answer 14

Okay.

Answer 15

so what do you think the domain would be?

Answer 16

So x=infinite?

Answer 17

well remember, domain refers to a range

so its from one number to another

Answer 18

I don't understand

Answer 19

domain refers to all possible x values in the function

it is generally written as a range of numbers,

ex.

(1, 100] means from 1 to exactly 100,
the parenthesis means that 1 is not included within the range
the bracket means up to exactly 100

in your case, its goes from 0 to infinity
but 0 is not included within the domain

Answer 20

So how would I determine the domain?

Answer 21

y=log5(2x+2)+5

ok now remember, for logn( )
where n is any number
whatever is within the parenthesis cannot be 0 and can go up to infinity
basically, 0 is the lower limit of the domain
infinity is the upper limit of the domain


so we start by looking at the expression within log5

2x+2
the lowest limit is zero, so
2x+2= 0
and we solve for x

Answer 22

x can't be zero.

Answer 23

ln(x) = y is the same exact thing as e^y = x. is there any way 2.7^? = 0

Answer 24

or < 0...

Answer 25

Wait, I don't understand.