Suppose that is differentiable at . Prove that for every , exists and is equal to
My work:
Let , then there exists an open set such that . Let
Find such that
Pick such that
Then there exists such that and
Am I doing this right so far? Thanks.
Suppose that is differentiable at . Prove that for every , exists and is equal to
My work:
Let , then there exists an open set such that . Let
Find such that
Pick such that
Then there exists such that and
Am I doing this right so far? Thanks.