#i need help finding the domain of log(sin(x))
26 messages · Page 1 of 1 (latest)
what i got so far is that
f(x) = log(x) and g(x) = sin(x)
and i put it into the formula but im not sure what to do
since the dom(sin(x)) would be {x ∈ R} and dom(log(x)) would be {x ∈ R | x > 0}
but if i put into the formula
then i get {x ∈ R | sin(x) ∈ x > 0}
but im not sure what to do next
ohh ok thanks
do you know if you can help me out with finding the range?
if you have the time
Sure.
ill show you my working out
So we know that sin(x) oscillates between -1 and 1, but in order to abide our restriction its going to be restricted to 0 < sin(x) <= 1. Note this is our input. Now the smaller the input the larger the negative exponent. Ex. log_10_(10^-1), log_10_(10^-10) as our input gets smaller and smaller i.e infinitely small towards 0, the larger the negative exponent gets. Now our largest input is 1. log_10_(1) = 0. Therefore I'd say the range is y <= 0
the formula to find the range(f(g(x)) is f(range(g) ∩ dom(f))
let f(x) = log(x) and let g(x) = sin(x)
so first i found the range(sin(x)) which was:
-1 ≤ x ≤ 1
then the domain of log(x) which was:
x > 0
then i substitute into the formula which got me:
log(x)(-1 ≤ x ≤ 1 ∩ x > 0)
and now i dont know what to do next
Don't know how to express it with your notation
oh thanks, im gonna give myself a moment to try to understand it
wdym by my notation?
The notation that you are using, I was not taught that notation.
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