University Maths Notes: Complex Analysis – Using Cauchy's Integral Formula
Cauchy's integral formula states
and
can be used in the following way.
Evaluate
where
is
the circle![]()
![]()
is
entire and
is
in the interior of
hence
![]()
Evaluate
where
is
the circle![]()
which
in the interior of
is
entire hence
![]()
Evaluate
where
is
the circle![]()
has
roots
both
inside
so
we write
and
separate the integrand into partial fractions, obtaining
![]()
sin z is entire hence
![]()
Evaluate
where
is
the circle![]()
lie
inside
but
-2 is outside. We rewrite the integrand using partial fractions.
![]()
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