- #1
trap101
- 342
- 0
Let f: R-->R be defined by f(x) = x(sin(1/x)) if x ≠ 0, f(0) = 0
Show that f is continuous at every point and diffeentiable at every point except x = 0
Attempt:
So I must be having a brain freeze, but to show continuity of a function without going through the delta-epsilon method which I don't think they want, I should just take the limit of an arbitrary number "a" and then:
lim x-->a f(x) = a(sin(1/a), but this doesn't feel like that is all that I'm doing.
Now for differentiability, I'm suppose to use the definition:
if there exists a value "m" and E(h) such that:
f(a+h) = f(a) + mh + E(h) then the function is differentiable.
Using that am I suppose to just solve for m and take the limit as h-->0:
m = [(a+h)(sin(1/(a+h)) - a(sin(1/a))]/ h ?
If that's the case then I'm stuck on solving for "m"
Show that f is continuous at every point and diffeentiable at every point except x = 0
Attempt:
So I must be having a brain freeze, but to show continuity of a function without going through the delta-epsilon method which I don't think they want, I should just take the limit of an arbitrary number "a" and then:
lim x-->a f(x) = a(sin(1/a), but this doesn't feel like that is all that I'm doing.
Now for differentiability, I'm suppose to use the definition:
if there exists a value "m" and E(h) such that:
f(a+h) = f(a) + mh + E(h) then the function is differentiable.
Using that am I suppose to just solve for m and take the limit as h-->0:
m = [(a+h)(sin(1/(a+h)) - a(sin(1/a))]/ h ?
If that's the case then I'm stuck on solving for "m"