This may be a stupid question thats gonna easily be proved but i just wondered at which step is this wrong. This is taken from a proof in my uni class that limit x->3 (7x) = 21 but just changing one number. why is it wrong and where does it go wrong?
Prove using the
definition of a limit that
(was originally 21 of course)
Rough Work:
|f(x) - L| = |7x - 28| = 7|x - 4|
|x - p| we can control with
If
, then
Proof.
Let
be given. Choose
, then if
=>
From the
definition of a limit,
Can somebody point out the mistake in that? surely there must be some step thats wrong!