Question

Find the Domain.

x-9/x^2-81

Answer 1

x-9 x-9 1
--------- = ------------ = -------
(x)² - (9)² (x+9) (x-9) x+9

now u can do the rest.....................

Answer 2

x-9 1
--------- = ------ solutions are all numbers without -9 than the denominator is
(x-9)(x+9) x+9

zero

Answer 3

domain is all real numbers except x=-9 and x=9

Answer 4

thats what i thought too but it keeps saying its wrong on my hw

Answer 5

you have a hole in the function at x=9 (so there is discontinuity here)
you have that the function has a vertical asymptote at x=-9(so there is discontinuity here)
the function is continuous on its domain
since the function is not continuous at x=9 and x=-9
then these numbers are not elements of the domain

Answer 6

all real numbers but x=9 and x=-9 is the answer
if it is saying it is wrong then it is wrong unless you function is not
\[f(x)=\frac{x-9}{x^2-81}\]

Answer 7

oh nvm.. it wanted me to not check all real numbers.. which is weird bc i dont know why it wouldnt want me to include that in the answer? any ideas?

Answer 8

what does your question exactly say?

Answer 9

It says: Find the Domain. then it gave me the function then the directions were select all that apply.. & i had originally checked in [all real number, x does not equal -9 and x does not equal 9] but when i submitted it it said wrong so i tried it without all real numbers and it was correct.. weird

Answer 10

that is weird
so there were 2 options one saying
all real numbers, x doesn't =-9 and x doesn't =9
and
another saying
x doesn't=-9 and x doesn't =9
?

Answer 11

but it said you could select more than one right?

Answer 12

you should select both then and i don't know what the other choices are but i know you should select both of those

Answer 13

no.. for example: all real numbers would be a option, x does not equal 9 would be a option and so forth. and you would check the box next to them

Answer 14

so it was correct when i excluded all real numbers and im not really sure why it would have me do that

Answer 15

well it isn't all real numbers
because we are excluding 9 and -9

Answer 16

and 9 and -9 are real numbers

Answer 17

ohhh that makes sense!

Answer 18

the whole set of real numbers is not domain
the real numbers - x=-9 and x=9 is the domain

Answer 19

oh ok , got cha! thanks! its so simple lol

Answer 20

yes but that is kindof confusing i suppose
its like they want to trick you

Answer 21

lol

Answer 22

haha yeah it seemed that way. thank you.

Answer 23

np