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kathrynag
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Homework Statement
Define h(x)=x^3sin(1/x) for x[tex]\neq[/tex]0. and h(0)=0. Show h is differentiable everywhere and that h is cont everywhere, but fails to have a derivative at one point.
Homework Equations
The Attempt at a Solution
[h(x)-h(0)]/[x-0]=x^2sin(1/x)
h is diff everywhere because the limit exists and we know x[tex]\equiv[/tex]0.
h'(x)=3x^2sin(1/x)-xcos(1/x)
We know f is diff at [tex]x_{0}[/tex], then f must be continuous at [tex]x_{0}[/tex].
h has a derivative at x if x[tex]\neq[/tex]0.